Diane Miller, who led the conversion of the former Vauxhall Astra factory at Ellesmere Port into the UK’s first and only dedicated volume electric LCV manufacturing plant, discusses her leadership style with Lynda Ennis, Co-founder and CEO of Ennis & Co Group.
Lynda Ennis: You’ve had an amazing career in the automotive industry, beginning with an engineering degree and rising to become Stellantis’s most senior UK manufacturing executive. Tell me about your journey.
Diane Miller: Well, I attended a girls’ convent grammar school and was one of only three girls in my year who did physics for A level. Our teacher was really interested in engineering and so all three of us ended up studying some form of engineering at university. I did a degree in mechanical and production engineering at Liverpool John Moores University and, through the ‘jobs milk round’, I was offered an interview by Ford. This included a visit to Ford’s Dagenham plant, where I saw them making 60 Fiestas an hour. The thought that they could make so many cars every hour really blew me away, and it still impresses me even now when I sit back and take stock of the plant. Since that moment in Dagenham, I’ve always been passionate about automotive.
I started work at the Dagenham assembly plant, which was a tough environment back in 1991, and I quickly learned that the best way to improve efficiency was to speak to the operators on the line because they always know the best way to do things quickly and in the smartest way. I saw a lot of engineers come in with a long list of qualifications and try to tell the operators what to do, but that never works in my experience. It’s much better if you can get the operators’ trust and buy-in, and that was very much the approach I took. Since then, I’ve always held onto the belief that you can do anything if everybody works together and everybody is encouraged to come up with ideas.
Quite quickly, I was promoted to Senior Process Engineer and, after about seven years, I was given my first management role, which was in the paint shop. I didn’t know anything about paint engineering at the time but, because it was a management position, I was able to use my people skills and learn about paint as I went along.
As part of the Ford 2000 globalisation strategy, we had regular visits and interactions with American colleagues at Dagenham and I was offered the chance to move to Chicago to train as a Paint Unit Manager for the plant programme in the United States. As part of the training, I was working as a Shift Manager but, after about six months, I was told the money had run out and they couldn’t afford to keep training me any longer. Instead, they wanted me to go straight into the Paint Unit Manager job at the Chicago assembly plant. Being thrown into the deep end was quite scary at the time because suddenly the paint shop was my unit and it was my responsibility to make it work. But being on the job was a great way to learn and it worked out really well. I was initially supposed to do the job for two years but Ford ended up extending it to four. I also met my husband out there and, when I came back to the UK in 2005, he came with me.
On my return, I worked as the Paint Unit Manager at the Ford Transit plant at Southampton before going on maternity leave for the birth of my son. While I was on leave, the Plant Manager at Southampton moved to the Aston Martin plant, which was owned by Ford at the time, and he asked me to join him as Paint Operations Manager. This proved to be a fantastic experience but completely different to what I had experienced previously. Going there, I thought working with a very low volume would be easier but it’s actually much harder because there’s no momentum. There’s a lot more for people to learn and the work is a lot harder than the standard work on the line.
After Ford sold Aston Martin in 2007, I had the choice of going back to Essex or staying with Aston Martin. I decided to stay because, by that time, I had two young children and didn’t want the disruption. I ended up staying with the company for seven years until, out of the blue, I was called by a headhunter about a Paint Operations Manager role at Vauxhall’s plant in Ellesmere Port, where they were launching a new Astra model but were having major problems with their paint shop. On this occasion, it seemed the right time to make the move and join GM.
I joined the company with sufficient seniority to make the necessary changes for a successful Astra launch and thoroughly enjoyed it. After more than six years in the paint shop, I was asked to take over general assembly, again using my skills to get people to tell me where they were experiencing difficulties. Two years later, I was promoted to Plant Director.
During my time at Ellesmere Port, Vauxhall was sold to PSA in 2017, and then PSA merged with FCA to form Stellantis in 2021. Within a couple of months of stepping up into the Plant Director role, Astra production ended at Ellesmere Port. Then came the ‘out of the blue’ decision to start making Stellantis electric vans in the plant, requiring me to oversee the closure of the factory for 18 months to convert it to EV production, which was a completely new experience for me. The first electric vans started rolling off the lines in September 2023.
Having led the EV factory conversion, I moved into my current role earlier this year as Director of Stellantis’s new Parts Distribution Centre, just down the road from the plant at Ellesmere.
“I quickly learned that the best way to improve efficiency was to speak to the operators on the line because they always know the best way to do things quickly and in the smartest way.”
LE: When you are part of the huge global organisation, how do you ensure that the way you lead on a local level is aligned with the values and culture of the parent company?
DM: When I moved to Ellesmere Port, Vauxhall was very independent and I didn’t notice a huge amount of GM influence but this changed when we became PSA. The CEO, Carlos Tavares, had a very strong focus on everyone within the organisation having the same values and he came into the plant and told us that we needed to benchmark against the plant in Madrid. All our managers went out to Madrid and then came back and implemented what they learned, delivering a big improvement.
The culture with PSA was very much around ‘you can make anything happen’. When we merged to become Stellantis and consequently became much bigger, there were more checks and balances and less freedom to do your own thing to make things happen. To be honest, my approach was to tell the plant to keep doing what they were doing so far as we could and ask for forgiveness rather than permission. Of course, you need to listen to the company but you must also make things work at the local level.
LE: Looking back at your career, have the leadership skills you have needed been the same, irrespective of who you were working for. Do the same leaderships skills apply now that you’re part of a big multinational group?
DM: Moving from Ford to Aston Martin to GM, there was no difference in the skills I needed. To me, they were identical. Stellantis, on the other hand, was different. They were much more detailed in how they followed up on things such as the cost per car, which Ford and GM didn’t do to that level of detail. With Stellantis, because I was closely involved in the growth strategy I found it very interesting, but the culture was definitely different to what I had experienced before.
LE: Has your leadership style changed as you’ve progressed in your career from managing a particular area to being responsible for the whole plant?
DM: As I mentioned, when I started I would go direct to the operators and ask them what they thought, and, to this day, I will still to do that. So long as they know I won’t over-react, I’ll let them say anything. I’ll give my opinion but I won’t hold grudges against people who give me theirs.
As I’ve moved into more senior roles, the difference has been trying to get everyone to think like that. Only yesterday, I had a had a conversation with a supervisor who didn’t like what the team leader was saying because it wasn’t the supervisor’s idea. I said, ‘What’s the problem with it? This team leader is passionate. Yes, there are a few things you don’t like about it, but listen to him and let him try it. If you tell him you’re worried about certain things, he’ll come up with another idea.’
Too many people at supervisor level, and even worse at management level, won’t listen to people when they come up with ideas. Even if the idea is rubbish, don’t just say so but say you’ll look at it, otherwise they’ll never offer you another idea.
LE: Do you think plants are now less hierarchical and regimented than they used to be. Is there more freedom for people to give their opinions?
DM: There are some people who think in a regimented way but, overall, I think it’s definitely less regimented now. We do have a structure but I’ll tell the team leaders that if something isn’t giving you value, tell me about what will give you value and then track that instead. Don’t track something just to say you’re tracking it if doesn’t bring any value to you.
LE: Are you seeing any more diversity now, not just in terms of gender but in other areas of DE&I?
DM: Well in terms of gender diversity, it’s still very male-dominated because we just don’t get the applications from women. In theory, women make up half the population but you can’t expect a 50% gender balance because they simply don’t apply.
More generally, I think there’s a huge opportunity in a plant for neurodiverse people, and I’m currently working with some local neurodiversity charities. For some neurodiverse people, it might take them longer to learn the job but, once they do, the quality of their work is likely to be better than people who are easily distracted. When it comes to some of my most technical people, I’m sure a lot of them are neurodivergent because they prefer not to work with other people but they give us what we need, doing a highly technical job that few people can do. We haven’t gone out looking for these kinds of personality types. It’s just happened naturally.
“Women make up half the population but you can’t expect a 50% gender balance because they simply don’t apply.”
LE: You’ve won awards for your success in manufacturing, particularly with the electrification Ellesmere Port. What were the key ingredients in pulling off such an amazing achievement?
DM: It was completely different to what I was used to because the factory was like a building site. All our day-to-day work was gone and the place was just pulled apart, which meant my role was more like a construction manager. We had to follow construction regulations, including implementing strict health and safety protocols, and we were responding to different issues every day as we coordinated a huge number of contractors. It was really, really interesting but completely different to my previous life of making 60 or whatever cars an hour.
A key aspect of my role was managing the teams of contractors. Some would try to blame the plant for certain things, while others would want to work collaboratively with the plant, so it was all about fostering relationships. As a plant, standing back and just saying ‘deliver this for us’ would never have worked. One of the best parts was the fact that about 300 of our hourly people stayed with us during the blackout period and did amazing jobs that they would never normally do.
LE: Thinking about individuals in the middle stage of their career, what do you feel we can do to better to equip emerging talent for tomorrow’s leadership roles?
DM: I think we have to take risks and put them in positions that are not traditionally given to young people, but there are two obstacles to this. The first is that if you’re a General Assembly Manager and you’ve got a very good person working for you, you don’t want to risk them going somewhere else so you put the brakes on their progress. Second, if you’re a manager and you put someone in a position only for them to fail, you worry that it will reflect badly on you and so you don’t take the risk. In my view, though, there is very little risk in promoting someone. I’ve been in situations myself where I’ve asked people to go into a job for six months with the promise that if they decide it’s really not for them, I’ll take them out again. Similarly, if we decide that it’s not working out after six months, we’ll take the decision to take them out without it impacting the rest of their career.
“I think we have to take risks and put them in positions that are not traditionally given to young people.”
LE: In terms of what people can do to equip themselves in the middle part of their careers, my observation is that dial has moved post-Covid and that more people are placing greater emphasis on work-life balance than making the sacrifices or putting in the hard yards to become the leaders of the future.
DM: Looking at it another way, there needs to be opportunities for talented people in the middle part of their careers to take the next step, and maybe the current leaders are not as encouraging as they should be. But I agree that there are people who want to stay at home and work remotely, which is a big change from when I was growing up in the industry. I think people had a stronger work ethic then and were more intent on making things happen. A lot of them also needed money, so would do lots of hours.
LE: Who are the people who have inspired you most in your career?
DM: The first person I would name is Mona Reinhardt, who was the Assistant Plant Manager when I went to the Chicago assembly plant in 2000. Having a woman in that kind of role was certainly unusual both in the US and in the UK at that time, and what impressed me most about her was that she had a maternal approach and didn’t modify her management style in any way. In the past, I think a lot of women thought they could only compete in a male-dominated environment if they behaved like men. She gave me the confidence to know that I could lead and be a manager by being myself.
Currently at Stellantis, I would say that Alison Jones is a big inspiration. She is a very honest and open person who will tell you things that went wrong for her or that really upset her through
her career. Hearing that things like that can happen even at her senior level is very reassuring.
LE: Final question… what advice would you give to your younger self embarking on a career in automotive?
DM: Take every opportunity you’re given. I did that and it was really scary at the start, but once you take the leap, you learn that you can do it.
The other thing I would say is, be true to yourself and don’t be afraid to say you don’t know. At the start of my career, I was comfortable telling people on the shop floor that I didn’t know something, but I would never have sat in a management meeting and say, ‘I don’t know what you’re talking about’. Now I can. Now I can say, ‘Can you explain it? Can you teach me?’
“Take every opportunity you’re given. I did that and it was really scary at the start, but once you take the leap, you learn that you can do it.”
