The procession, led by triple cycling gold medallist Chris Hoy, started at Mansion House following a reception with the Lord Mayor of London at Guildhall.

The athletes on 12 floats went through St Paul's, Fleet Street and the Strand before gathering in a packed Trafalgar Square.

All the athletes who went to Beijing had been invited and it was the first time so many of them were able to come together since their return.

"It's just unbelievable," Hoy said, "Everybody's so happy and it 's great to see so much positivity."

"It's a nice feeling. It's the stuff of dreams."

Team GB returned from Beijing in August with their best Olympic medal haul in 100 years, winning 19 golds, 13 silvers and 15 bronze for a fourth place in the medal table.

Their Paralympic team were also successful, finishing second behind hosts China with 102 medals including 42 golds.

After the parade, the Olympians will go to Buckingham Palace for a reception with the Queen, the Duke of Edinburgh and the Princess Royal, who is President of the British Olympic Association.

Princess Anne competed at the 1976 Olympics in the eventing competition.

A Royal reception for the Paralympians will be held early next year.

The fans who went out to welcome the parade considered it a deserved tribute to their heroes.

"I'm really proud of them", said Judith Andrews, who is working in the city and got a special break to watch the procession with her boss.

She went to cheer particularly for Lee Person, who collected three dressage gold medals at the Beijing Paralympics to take his career tally to nine.

"He's my hero. He's disabled but it's amazing to see him in competition. I did dressage myself so I know how difficult it is. But he won nine medals."