Video report by ITV News Correspondent Rupert Evelyn
The G-CIVB and G-CIVY 747 models took off in foul weather shortly after 8.30am on Thursday.
The jumbo jets, one of which is painted in the BA heritage “Negus” livery, had been due to perform a rarely seen synchronised dual take-off on parallel runways, but were unable to do so due to the rain.
It comes following the retirement of the airline’s fleet of 747-400, which was brought forward as a result of the impact the Covid-19 pandemic has had on the airline and the aviation sector.
BA's Boeing 747 landed in St Athans, Wales after departing Heathrow for the final time:
It was live-streamed on the airline’s Facebook page, with enthusiasts and customers encouraged to share any special memories or photos of British Airways’ 747s at 7.47am and 7.47pm using the hashtag #BA747farewell.
Some 18,000 people tuned in to watch the final flights.
Launched in 1969, the planes were considerably larger than existing airliners, with a capacity of around 550 passengers.
They were known by British Airways as The Queen Of The Skies.
The airline once boasted the world’s largest fleet of the 747-400 model with 31 aircraft.
Speaking on Wednesday, Alex Cruz, British Airways chairman and CEO, said “Tomorrow will be a difficult day for everybody at British Airways as the aircraft leaves our home at Heathrow for the very last time.
“We will pay tribute to them for the incredible part they have played in our 100-year history and to the millions of customers and BA colleagues who have flown on board and taken care of them.
“We hope that Britain will join us in sharing their memories with us on social media at 7.47am and 7.47pm on Thursday using #BA747farewell.”
The 747 fleet is to be replaced by quieter, more fuel-efficient aircraft as part of the airline’s commitment to achieving net zero carbon emissions by 2050.
The airline expects the last 747s, currently positioned in Wales, to leave the fleet by the end of the year.