That's quite a big piece on the BBC news website that DMcG is quoting from. Perhaps Nigel will see it tomorrow post-duvet time. Three wheels on my wagon...
I saw it, I read it. I quoted from a further link at the bottom of that same page.

Raggytash posted the original link.

DMcG's quote: SMMT chief executive Mike Hawes said at the time: "Brexit uncertainty, coupled with confusion over diesel taxation and air quality plans, continues to impact domestic demand for new cars and, with it, production output." which he commented on as "Brexit explicitly blamed".
While the quote mentions Brexit, it also links in other factors (diesel taxation and air quality plans).
The article doesn't give figures for the reduction in output specific for JLR, but it does give a figure of a 5.7% reduction in UK (and Europe?) in 2017.
As the other article from the same source (which I linked to) gives JLR hitting a record high in 2017, it appears that sales to the rest of the world are more than making up for reduced sales to UK & EU.