"I have a theory that there is something about these services such as iTunes and Napster which is sparking an interest in music which is leading to increase physical sales.

"The people joining legal services are music fans who have a chance to get excited about music again.

"What we are most happy about, so far, most people who are consuming music online are buying CDs as well."

Keith Jopling, head of market research at the International Federation for the Phonographic Industry