Sir Cliff Richard often wakes up in the middle of the night in a panic about forgetting the words to his songs.

Although the 71-year-old musician has been performing for over 50 years nerves can still get to him, especially when he is getting ready to add new songs to his repertoire.

He explained: "It's not possible to break the habit of being nervous. You kind of know what you can do now and so you think 'I can do that' But then you start rehearsing and you've got songs you have never sung before and you wake up at night going, 'I can't get through the lyrics', then you start to panic so by the time you get to that first or second show you're still now sure that when you get out there on stage and smile if your brain is going to remember the lyrics. It happens to me sometimes, I smile and go, 'Oh no, I've forgotten the lyrics.' So all that causes a nervous tension, but once you've done one or two shows and nothing's gone wrong, you start to relax then and enjoy it."

Cliff recently performed a host of new songs with a selection of musical legends including Lamont Dozier and Percy Sledge on his 'Soulicious' tour and while he loved working with them, he also enjoyed the chance to take a break while they sang their own hits.

He said: "When David Gest [producer] first mentioned the idea and told me all of the people he wanted to work on the album, Marilyn Mccoo & Billy Davis, Jr., Lamont Dozier, Jaki Graham, James Ingram, Freda Payne and Percy Sledge and I didn't think we could get them all but then they all showed up and it's fantastic.

"For the show of course I couldn't get them all together at the one time because they're so busy but I think that the way it worked out was actually best. It would have been wrong to have everyone over together so this way it gave me plenty of time to do my hits which allows us to do the eight duets which were the new songs and then each of my guests sang their own hits which the audience loved.

"And also have the help of six other people on stage meant that there were six times when I could go off stage and change my clothes and take a bit of a break."

The 'Cliff Richard: The Soulicious Tour' DVD is out now.