"I remember watching the Coronation on TV, she has been Queen almost as long as I've been alive, she has been a constant, and I think she's done an amazing job under difficult circumstances sometimes, so I'm more jazzed about doing this than ever... for her," he said.

Sir Elton, who is still recovering after being rushed into hospital last week with pneumonia, is just one of the superstar line-up thrilled to be invited to perform at the Buckingham Palace gig, which is being billed as the centre piece of the jubilee celebrations.

Sir Tom Jones, who is also in his seventies, is clearly touched to be involved, telling Sky News: "When I had my OBE and Knighthood the Queen pinned it on, so it's like wow you cannot get any better than that."

He added: "I'm glad to see she's healthy and enjoying it, it doesn't seem like a chore. She does it well with style and grace, it's a wonderful thing."

The Queen and Prince Charles will make an appearance on stage at the concert alongside rock and pop royalty during the three-hour musical extravaganza, which has been masterminded by Gary Barlow.

Most members of the royal family have already taken their places in a specially built stand to watch the concert from.

The Queen Victoria memorial stage will have an audience of 10,000 people who received tickets through a ballot, with a further 500,000 watching on big screens in St James's Park, Green Park and The Mall, and millions more viewing at home.

In addition to Sir Elton and Sir Tom, the line-up includes a wealth of artists who have spanned the Queen's reign, such as Sir Paul McCartney, Sir Cliff Richard, Cheryl Cole, Stevie Wonder, Kylie Minogue, JLS and Jessie J.

Dame Shirley Bassey will sing Diamonds Are Forever, Sir Paul will play Live And Let Die, while Sir Elton will perform Your Song, I'm Still Standing and Crocodile Rock.

Sir Tom is expected to sing Delilah and Mama Told Me Not To Come and Robbie Williams will perform Mack The Knife.

Gary Barlow - who is also set to duet with Cheryl Cole - will do his official Diamond Jubilee song, before Madness take to the top of Buckingham Palace for the event's finale.

The host of stars will entertain royal guests including the Duchess of Cornwall, the Duke and Duchess of Cambridge, Princess Anne and Princes Harry, Andrew and Edward.

Sir Cliff told Sky News: "I don't think you ever get used to being invited back again and again and again.

"I couldn't believe when I read in a paper that the Queen said 'Oh I'd like Cliff to be there' - and I'm thinking she probably didn't say that - but it's nice to think I'm still considered part of the fabric of society as are Elton, Tom and Paul."

The single Sing! has also been released as part of the festivities.

Written by Barlow and Lord Lloyd Webber it celebrates the Commonwealth and the Queen with the track featuring singers from around the world as well as Prince Harry playing the tambourine.

Sing! is the title track song on the official Diamond Jubilee album which has shot to the top of the UK charts.

The Military Wives conducted by Gareth Malone - who were the Christmas number 1 - have also contributed to the track and will perform at the concert.

Malone told Sky News: "I got a tweet from Gary Barlow saying do you want to come and have a cup of tea and you don't say no to Gary Barlow do you?

"I went and met him and he sang the song to me face to face. It was a very intense experience because I then had to tell him whether I liked it or not. Happily I did."

Rebecca Marshall of the Military Wives said: "She certainly likes the song, we've been told she is a fan and that's all you need, as long as the Queen is a fan of the song everyone has got to enjoy it."