By Antony Thorncroft

Next Thursday is Beatles Day, which will be celebrated fervently in Liverpool, the band’s hometown, and just as enthusiastically at Christie’s in London’s South Kensington. The saleroom is holding its annual British auction of pop memorabilia to mark the event.

The Beatles dominate the pop memorabilia market and around half of the 264 lots on offer in this sale relate to the group - including all the most costly items. The undoubted star is John Lennon’s autograph lyrics for “Give Peace a Chance”. He wrote them during his notorious Montreal “bed-in” in 1969, and gave them to 16-year-old Gail Renard, who acted as gofer while John and Yoko Ono spent a week in bed in aid of peace.

Lyrics by The Beatles are the holy grail of pop memorabilia, and Christie’s expert Helen Hall could hardly believe her luck when Ms Renard appeared with the written lyrics. She put a top estimate of £300,000 on the lot. Beatles lyrics have become so rare they could rival the record £690,000 paid in July 2005 at specialist pop dealers Cooper Owen for another Lennon song, “All You Need is Love”.

Equally famous is the drum skin, hand-painted by pop artist Peter Blake, featured on the cover of the Beatles’ Sgt Pepper’s Lonely Hearts Club Band album. Discovered abandoned in 1994, it sold at Sotheby’s for £50,000: this time round, it carries a top estimate of £150,000. Although most buyers are ageing Beatles fans who can now afford to invest in youthful nostalgia, there is a growing influx of new buyers, many of whom also collect contemporary art. Some are caught up in the myth, while others have an eye for an investment: The Beatles have become the gold-plated securities of pop memorabilia.

If handwritten lyrics remain the serious collector’s dream, there is also intense interest in instruments played by The Beatles. These are very rare, although a George Harrison guitar has sold for $500,000. At the more affordable level the market is now quite mature, with prices rising gently for the stock items. An autograph book signed by all four Beatles should make up to £2,000, and a photograph nearer £3,000, while a signed cover from an early album goes for around £5,000. Everything depends upon condition and provenance but by now the specialists can spot the thousands of Beatles signatures written by roadies and secretaries.

Later Beatles material is rare and more expensive, with values appreciating since 2000: Bonhams recently sold a signed Sgt Pepper album for £16,500, and anyone with a signed Abbey Road is looking at upwards of £20,000. It is the unexpected items that attract the fiercest bidding: Bonhams was caught out in June when a Honda monkey bike owned by John Lennon and then Ringo Starr soared above its £7,000 estimate to make £36,000.

On Tuesday, Christie’s has an equally idiosyncratic item, the tinted glasses worn by John Lennon during 1973-74, a period known as the “Lost Weekend” when he lived apart from Yoko Ono: they carry a strong £30,000 top estimate. The long-dead Lennon remains the most commercially desirable Beatle (he holds the pop record with the £1.7m paid for his psychedelic Rolls Royce) because Paul McCartney memorabilia is in constant supply: a 2008 signature is worth around £200.

The only saleroom rival to The Beatles is Elvis Presley, but in recent years his market has been flooded, not least through the dispersal of the contents of his Graceland home by his widow Priscilla. He is now mostly traded on the internet.

Pop memorabilia can be a fickle business. A few years ago, Oasis ephemera was all the rage; now it is a bear market. Interest in Madonna, Robbie Williams and the Spice Girls has stalled, but Jimi Hendrix, Pink Floyd, Queen, The Rolling Stones, and The Who remain reliable performers, and the “punk era” is growing in popularity. On Thursday, Christie’s offers a poster promoting The Sex Pistols’ first Paris concert in 1976, estimated at up to £3,000.

The memorabilia market is a broad church, and there are sales embracing film and television ephemera, some of which seem under-priced.

Though no one is likely to rival The Beatles in saleroom popularity, it was a very different Lancashire entertainer who achieved the top price at Bonhams in June: George Formby. The goofy entertainer’s favourite banjolele sold for £72,000, three times its estimate, suggesting that the Formby catchphrase of “turned out nice again” still rings true - at least for the salerooms.

Rock & pop memorabilia at Christie’s South Kensington on July 10: www.christies.com