He attributed the move to “segment shifts" across Europe, highlighting the growing trend for SUVs in place of models such as the Astra, which is built at Ellesmere Port.
The news in October that the plant near Liverpool would scrap 400 roles came three months after French car maker PSA Group, which also owns Citroën, DS and Peugeot, completed its acquisition of Vauxhall and its European counterpart Opel.
At the time, PSA said manufacturing costs at Ellesmere Port were higher than other "benchmark plants" in the group.
The facility will move staff from two production shifts to one in early 2018.
Since then, PSA and Vauxhall/Opel has announced a turnaround plan that includes launching all cars on PSA platforms and setting the goal of keeping all current plants – including Ellesmere Port and Luton in the UK – open, although potentially on altered terms.
Harvey said today: “I'm very excited in terms of what's going on. There's a lot of transition, a lot of change. But if you look at some of the fundamentals now, we're moving very swiftly.
“One thing that isn't necessarily a positive, but happened on a voluntary basis, is that we took some cost out of the plant at Ellesmere Port and some people put their hand up to help us get to where we need to.