We certainly got away from Northeast Viscount 800s pretty quickly ! I suspect there was an element of passing the aircraft back and forth short term, BEA had a pretty long tradition of this with their various offshoots, who each seemed to be the first port of call for one another, leading to things like Comets on BEA services well after the official last flight (this was of course ones passed to Airtours, brought back to Heathrow during yet another Trident shortage). Cambrian One-Elevens, which often seemed to not have a lot to do, operating BEA internal German services out of Berlin, was another. Viscount 800s loaned to Cyprus Airways as cover for their dedicated two ... the list probably goes on.
These Viscount 800s probably had some sort of record for different airline names, and liveries, carried in short order. From the BEA Red Square scheme, I don't know if any went into the Speedjack scheme before going to BKS and the globe logo, followed by the Northeast yellow rebranding, then the BAS scheme which some had, and then back into British Airways initial colours, and on into Channel Islands or whatever. I make that seven names/liveries in about the same number of years. I haven't done the detail but likely someone can.
Cardiff was the Cambrian maintenance base, and in time became the all-BA Viscount centre, and where they were all stored as withdrawn. I wonder if any of the most senior 777 engineers there nowadays started on Viscounts.