Pretty clear that Brexit was one of the factors leading to the closure of Honda Swindon. Like FlyBMI, it is unlikely to be the only reason but it can well be the straw that breaks the camel's back.
David Bailey, an economics professor at Aston University has said “I think we’re seeing a collision between Brexit uncertainty making investment difficult, just as the industry is transforming itself. Honda came to the UK because it offered a launchpad into the single market. There’s a lot of bewilderment in Japan about Brexit because what we offered them has been taken away. We’re not upholding our side of the deal so they don’t need to either. There may have been more of a chance of the UK being a centre of electric vehicle production if we stayed in the single market and if we had a more supportive industrial strategy.”
https://www.theguardian.com/business...-close-in-2021