I believe BOAC did try and support British industry, it did order the Hermes and I have read that that had huge problems with performance and support.
The York, Halton and Lancastrian were all used immediately post war probably just because they were available, although unsuitable in real terms.
The Tudor could have been a winner but again fell short on payload range I believe.
The Comet and Concorde were real steps into the unknown and any operator was brave to pioneer their use. The Brittania too to a lesser extent.
That only leaves the VC10 which was/still is a good aircraft. I wonder what the operating cost comparison was for it and the 707/DC8.