After much discussion and thought, the "Railfreight" depot is now a "Zanussi" warehouse (special thanks and credit go to Nearholmer https://www.rmweb.co.uk/community/index.php?/profile/26817-nearholmer/ for the idea.)
The signage was easy enough to find online - one of them is for "Zanussi Professional" - I imagine this would be the industry arm of the business.
I decided to keep the Railfreight and BR logos in situ, I doubt it's very prototypical practice - but I think it looks ok.