Rifleman Michael Swain, who had both his legs amputated above the knee following the explosion in Afghanistan in November 2009, has undergone revolutionary surgery in Australia.
The 24-year-old soldier with Edinburgh-based 3 Rifles had titanium rods fused to his thigh bones in a procedure called osseointegration, which allow him to click on special prosthetic legs in a matter of seconds.
He said the new legs were "amazing" and more comfortable that the usual ones.
But he said he had been worried about falling over in front of the Queen when he went to pick up an MBE for the extensive charity work he has done since the explosion.
He said: "She said something to me about my work helping other people. Obviously it is a bit of a blur now, standing in front of her.
"I was just thinking 'don't fall over, don't fall over on those legs, don't fall over'."
He also joked that after wearing his uniform shoes he could not wait to put his trainers back on.
Rifleman Swain has a son, Max, three, with partner Jade Hardiman, 24, who is also expecting the couple's second child, a girl.
They live in Luton, Bedfordshire.
Miss Hardiman, who was at the castle today, said: "Now he is up on his legs it is the best he has been, it is so overwhelming.
"He has been an amazing dad, he had been in a wheelchair for three years while Max was little and he managed to do it."
The operations on his legs were carried out by Dr Munjed Al Muderis, a former Iraqi refugee who fled to Australia to escape Saddam Hussein's regime in 1999.