London 2012: David Cameron visits Paralympic Day
Prime Minister David Cameron was among the high-profile visitors to Trafalgar Square on International Paralympic Day.
The event was held to promote next year's Paralympic Games in London, for which tickets go on sale on Friday.
Mr Cameron and London Mayor Boris Johnson each partnered a wheelchair tennis player as they tried out the sport before an enthusiastic crowd.
The day ended with the official invitation being issued to athletes around the world to compete in 2012.
The Paralympics follow the Olympic Games and run from 29 August to 9 September next year.
Mr Johnson promised that paralympic athletes would be well looked after at the Games, saying: "We are really looking forward to welcoming the world's elite paralympians to the capital next year and they will receive a fantastic reception once they arrive in our great city."
London 2012 chairman Lord Coe said: "I want all the tickets to sell out and I think we have a very good chance of doing that.
"People get paralympic sport in this country. Our history in the paralympic movement and that many of our paralympians are household names gives us a real head start in this country."
The programme of events, featuring demonstrations of all 20 paralympic sports, coincided with the visit to London of representatives of the International Paralympic Committee (IPC).
The heads of National Paralympic Committees from more than 100 competing countries will have the chance to see many of the Games venues.
IPC president Sir Philip Craven said: "The foundations for what could be the most successful Games ever are being laid in London. All we need now is the athletes."
British swimmer Ellie Simmonds, who also attended the event, told the BBC: "It is good that the Paralympics is now getting on the same scale as the Olympics."
Great Britain wheelchair basketball player Ade Adepitan told the BBC how important playing the sport had been to him.
He said he had spent many years on calipers trying to play able-bodied sports with his friends.
"When I discovered wheelchair basketball it changed my life. I wouldn't be here if it wasn't for sport and I think sport is having the same impact on kids both disabled and able-bodied all over the world and that's what we hope we can do with 2012 too.
"This event is extremely important. Generally a lot of people know about the Paralympics, they might have seen a little bit of the sports on TV but here's an opportunity to come and meet the athletes watch the sports and the events live.
"When I spoke to a lot of my friends about myself playing wheelchair basketball they could not believe how hard it was, how fast it was and how big the players were."
Thursday's events kicked off at 0815 BST with the first round of sports being showcased and a world record attempt for the longest rally in a sitting volleyball match.
A non-competitive race between Pistorius, American Jerome Singleton and five local schoolchildren took place on a track in front of the National Gallery but the two athletes did not go to head-to-head because of safety concerns.
A bronze sculpture of Pistorius by artist Ben Dearnley was also due to be unveiled.
Pistorius told the BBC: "Athens was phenomenal, Beijing was on a higher scale with a bigger turnout and more coverage but I think London's going to be at the forefront.
"The coverage of today is getting phenomenal and the people are coming out and enjoying the sports.
"I have seen some people clench jaws seeing the wheelchairs clash (in the basketball) and that's exciting but that kind of excitement around the sports is what's needed and I'm looking forward to it.
"The Paralympics is still my first love. If you look at my career, one of the biggest highlights is Beijing's Paralympic Games. It is something that is extremely special to me."
One of the final session highlights was a penalty shoot-out with Great Britain's blind football five-a-side squad competing against former England internationals Ray Wilkins and Paul Merson, former professional Chris Kamara and youth team players from Chelsea and Swindon.