The Prime Minister watched as Claire Lomas, who became the first person to complete a marathon in a bionic suit, lit the cauldron from the English national flame kindled on Scafell Pike earlier this week.
Organisers have confirmed 2.3 million tickets have been sold for the Games so far, with London 2012 chairman Lord Coe predicting that spectators watching events for the first time will be “blown away”.
Speaking in Trafalgar Square yesterday, Mr Cameron said: “The Olympic Games made our country proud. I believe these Paralympic Games will make our country prouder still.
“Already this is shaping up to be the best, the biggest, the most incredible Paralympic Games ever. Over these next two weeks, we’re going to have more of those moments that will bring us together and make us proud.
“We are going to show the whole world that when it comes to putting on a show, there is no country like Britain and no city like London.”
Ms Lomas, who was left paralysed from the chest down following a horse-riding accident in 2007, walked the London Marathon earlier this year in a pioneering robotic suit, raising £204,000 for Spinal Research. The cauldron lighting in London will be followed by similar events in Belfast, Edinburgh and Cardiff on consecutive days over the bank holiday weekend.
The four national flames will then be brought together on Tuesday in Stoke Mandeville where they will create the Paralympic flame, signalling the start of the relay.
It will be carried 92 miles by 580 torchbearers, working in teams of five, to the Olympic Stadium in Stratford where it will be used to light the cauldron at Wednesday’s opening ceremony.
Meanwhile, Prince Harry has praised the “inspirational people” who will carry the Paralympic torch to mark the arrival of the Games.
The prince said in a video message published yesterday that torchbearers were the “embodiment of Paralympic values” as they prepare to carry the flame in a 24-hour relay before Wednesday’s opening ceremony.
Harry, who has been in the headlines this week after naked pictures emerged of him partying in Las Vegas, recorded the message in May, St James’s Palace said. In the message, Harry said: “Teams of inspirational people will carry the flame on an historic overnight relay to the Olympic stadium.
“They include those who have collectively overcome adversity through teamwork, those who have overcome many challenges and continue to push themselves to the limit and those who inspire to do more than we think is possible.
“These people are the embodiment of the Paralympic values. This is their moment and an opportunity for us to applaud and thank them for their achievements.”
Organisers said another 200,000 or so tickets were still to be sold for the Paralympics, with about half on sale before Games time.