Pop music is the greatest cultural phenomenon of the past 50 years and it was inevitable that its memorabilia – guitars, original lyrics, stage costumes and merchandise – would have a powerful impact on the world of collecting.

The Beatles provide the most sought-after items, some of which are gaining in value now most of the band members are either dead or retired. Since George Harrison’s death, the cost at auction of a programme signed by all four Beatles has almost doubled to around £5,000.