Yes it was Harold Wilson's Labour Government of about 1968 which insisted the National Short-Haul Airline buy British (a mix of Tridents including the Three and BAC111-500 ,with a subsidy, I believe) instead of the Boeing 727-200/737-200 mix they wanted, (on reflection BOAC were permitted to order the 747 around that time0.
The Thatcher Government oversaw the privatisation of the unified State Airline and allowed them to buy the equipment they chose
AFAIK. British Aerospace managed to get Government funding for the 146 airliner from Mrs Thatcher though