In the BOAC/BEA days when we actually had aircraft manufacturers producing entire aircraft rather than just the bits, they were strongly encouraged to ‘buy British’. This lead to aircraft being designed such as the VC10 with its good hot/high/short field performance ideal for routes to India / Africa etc. This carried a penalty in terms of economy and made it unattractive to operate in situations when hot/high performance was not critical. This was made worse by the early american jets where runway lengths were increase to accommodate them leaving the VC10 with no real need for hot/high performance and the cost of such performance.

BEA were also guilty of this with the Trident in that it was designed to suit BEA markets rather than a worldwide market.