Well-wishers gathered waving Union flags, cheering and shouting “Go Tim” as Major Peake and his two crew companions departed from the Cosmonaut Hotel for their flight.
He said goodbye to family and friends including his wife and two sons, Thomas, six and Oliver, four, and in a final Twitter message added: “Last tweet before launch — GO for flight! Thanks for all the good luck messages — phenomenal support!”
He strapped himself in 45 minutes before lift-off — having chosen three songs to entertain him during the wait: Queen’s Don’t Stop Me Now, U2’s Beautiful Day, and Coldplay’s A Sky Full Of Stars.
The rocket blasted off from Launch Pad 1 — the spot from which Yuri Gagarin became the first man in space in April 1961.
The crew were orbiting earth at 17,500mph and were due to dock at the ISS at 5.23pm British time at the start of a six-month mission.
Only five British-born people have gone into space before. The first, Helen Sharman, was on a privately funded mission in 1991 and the other four had taken US citizenship.
Ms Sharman was at the Science Museum with 2,500 children and guests including science minister Jo Johnson and his children, all excitedly awaiting the launch.
They were joined by cosmonaut Alexey Leonov, who in 1965 was the first man to walk in space.
The museum’s senior curator Doug Millard said: “This is hugely important. We’ve finally arrived at the top table.
“Tim Peake’s flight is very much for the nation. So much of what he’s going to be doing during his six months is geared to education, talking to schools, experiments, even doing the London Marathon while he’s in space.”
Ms Sharman added: “Today is very exciting. We’re going to have Britain put on the map again in terms of international collaborative space flight.”
Mr Johnson said: “This is a fantastic moment. We’re putting the first man with a Union Jack on his shoulder into space. Next stop: Mars, Mercury, Jupiter by 2023.”
The Government unveiled its national space policy two days before the mission. It includes investments in spaceflight and microgravity research that it claims will give an £11.8 billion boost to the economy.
Among the 2,500 schoolchildren waving Union Jacks at the Science Museum were 60 pupils from Wolf Fields primary in Southall who have been tracking Major Peake’s progress as part of their classes.
