Just had a brainstorm, I have a 2014 RRS (L494) which as you'll know is very closely related to the D5 in so much as they're based on the same chassis (albeit shortened for the RRS).
I'm normally on sister sites to this one: disco3.co.uk and fullfatrr.com, also run by Martin L, but have been trying to help a neighbour with his 'new to him' 2020 Disco 5.