What finally ended up as the Belfast started off as the "Britannic" proposal in 1958, with basically a Britannia wing and tail surfaces with various engine options- the wingspan also growing by 20ft. There was a range of 6 Britannic variants proposed, the last with V.C. 10 type swept wings. The entire evolution saga was very complex and involved several companies.
Eventually a production of 30 was envisaged to make it viable. However once this was in progress the order was cut back to 10.
The Starlifter wing and tail version was a later proposal.