Collectors gain a rare opportunity to bid on George Michael’s 1940s Gretsch Synchromatic 400 when Sworders offers the instrument at auction on 29 October, with the lot estimated at £100,000.

The guitar comes from the archive of Siobhan Bailey, Michael’s personal assistant for more than 20 years, who died in 2014. Sworders has grouped the Gretsch with a broader collection of paperwork and memorabilia from Wham! and George Michael, including tour itineraries from their 1985 visit to China. Those itineraries carry modest estimates between £300 and £600.

The sale also lists a gold disc awarded for 500,000 UK sales of Wake Me Up Before You Go-Go, with a lower estimate of £200, and Sworders values the entire Bailey archive at more than £200,000. Guy Schooling, chairman of Sworders, called the Faith guitar the “jewel in the crown” of the collection. He said, "The sale will offer avid fans around the globe, the chance to own not just pieces of music history, but objects that capture the spirit and ambition of one of pop's greatest and most-loved artists."

Several replicas of the Gretsch were produced for the Faith tour, and the market for George Michael items has shown appetite at the high end. Earlier this year Propstore sold the leather jacket Michael wore in the Faith video for £176,400. Propstore will also offer the Ray-Ban sunglasses he wore on stage during the 1988 Faith Tour in a two-day auction beginning on 1 October, with those glasses expected to fetch at least £15,000.

For buyers the Sworders lot is a rare artefact linked to a solo album that sold more than 25 million copies worldwide, and for the market it will supply another data point on value. The combined timing of the Propstore and Sworders sales concentrates attention on Michael’s memorabilia, drawing both serious collectors and casual bidders to a spectrum of lots that ranges from low-cost tour papers to marquee pieces with five-figure expectations.