Charlie Crick, who suffers from a terminal congenital heart disease, was invited to Number 11 on Tuesday last week to celebrate the 10th anniversary of children's charity Rays of Sunshine.
Among the guests were children who had previously had wishes granted by the charity - like 15-year-old Charlie - and celebrity supporters Aston and JB from JLS, Molly, Una and Vanessa from The Saturdays, Dynamo the Magician and Kimberley Walsh.
Chancellor George Osborne, who hosted the party, said: "As well as taking part in crafts and getting to meet some of their heroes, they brought some rays of sunshine into Number 11."
Charlie got the chance to meet JLS, his favourite band, earlier this year, thanks to a trip arranged by Rays of Sunshine after a request by the News as part of his 'bucket list' appeal. As part of his list, he has also met Olly Murs, been a judge on X Factor and made his own fizzy drink and chocolate bar.