Bryan,
There were four ships of this class built all for Hudson’s. They were, as you say, all laid up on completion, two in Liverpool and two on the West Float, Birkenhead. Apparently, Cammell Lairds expected to build over a hundred of them, I have heard 140, but it all fell through.
After the Falklands all four were purchased by the MOD, and renamed RFA Appleleaf, Brambelleaf, Bayleaf and Orangleaf, ex Balder London. The Apple was leased to the RAN and decommissioned in 2006 and is now and oil storage vessel in the Gulf. The Bramble was scrapped last year and the Bay will no doubt be the next. The Orange does have a larger GRT than the others but, all have the same dimensions.