In the Anglo Italian thread "1974: A Schism of Joint Promotions" we discover 1974 and the end of Morrell and Wryton Promotions really was the beginning of the end.
We know that Relwyskow continued as an independent entity from the rest of the deteriorating Joint Promotions empire, but the oddity is that in the 1980s we find the formerly great Dale Martin Promotions citing an address of 6 Oakwood Lane in Leeds. That's the address of Relwyskow Promotions. There's an example of this posted by Main Mask in Geographical Names.
So had the Dale Martin HQ in London closed down? When did Dale Martin Promotions become little more than a Post Office box in Leeds?
I don't know how it works in the UK, compared to NZ, but here you can have a business name and office and then several trading names. I wondered if Max (or Astaire) kept the older promotional names in use as trading names in the relevant areas.
I also have a slightly unrelated question; When DM moved to Nursery Road, did they also close the print shop?
Wild theory: was the London office maintained as it was a convenient location for Mike Marino to work out of and was no longer necessary following his death, coupled with Halifax-based Max essentially running the show?