Paddy had gone by the time I arrived at BA in '85 but I suspect it had a "standard" galley config and it was all the new to BA fleet that had "non-standard" galleys (from a global perspective rather than BA's). IIRC we tended to have bespoke insert & cart designs to mitigate thieving from unscrupulous airlines and handlers (and of course BA always knew best when it came to design/specification.....). I can't recall what we called them but they were definitely different to other standards eg ATLAS, KSSU. As an aside, when we took on the ex-Dan Air 737 fleet that was one of the biggest headaches - Dans had gone for the cheapest leases, irrespective of fleet commonality. When anything from that fleet went tech it was a nightmare swapping catering loads.
The suspicion of "free mods" has a ring of truth. Most leases had a non-prejudice clause in them so if you were doing a mod to your own fleet you had to do it to the lessors too (at your cost, not theirs). Because BA did very little leasing in back then, they weren't too savvy about lease contracts. Up against someone like Ryan they'd have been completely hoodwinked.