Minuscule football shorts, explosive perm, studied introspection... That'll be bassist John Deacon, then.

FREDDIE MERCURY, Brian May and Roger Taylor were instantly recognisable as they joined the Prince and Princess of Wales at the beginning of Live Aid on 13 July 1985. The fourth member of Queen, down on the list of honoured guests as bassist John Deacon, wasn't so familiar. "I'm a great fan and I really wanted to meet her," he said afterwards. "I was too nervous, so Spider our roadie met her in my place. When it came to it, I thought I'd make a fool of myself and not be able to think of anything interesting to say."

Queen was a band of extremes in all things, and in John Deacon - the last to join, in 1971 - they had the ultimate stereotypically anonymous bass player. Deacon's childhood passions included fishing and transistor radios, yet he was also a talented, versatile musician, having picked up the guitar at the age of 12 before switching to bass in his first band, The Opposition, three years later. Even then, he was noted for his quiet reserve. Briefly a mod, Deacon once crashed his mirror-festooned Vespa 180, an incident described by The Opposition's guitarist Dave "Pussy" Williams as "the only time I ever saw John stressed out!"

However, it was in Queen - where Mercury was flamboyant, Taylor insouciant and May the big-haired axe hero - that Deacon became the supreme Other Guy, happy to be an Indian in a band otherwise made up of chiefs.

On the band's debut he was credited as Deacon John because Mercury and Taylor thought it would make him sound more interesting. Although at his insistence this affectation was soon abandoned. "In the early days, I used to be very quiet because I always felt I was the new boy," he said. "But I think I fitted in because of that. They'd tried several other bass players before me, but their personalities seemed to clash. I was alright because I wasn't going to upstage Brian or Freddie."

EVEN AS QUEEN'S popularity snowballed, John Deacon remained an enigmatic figure. In concert during the imperial Mercury moustache era, frontman Freddie prowled under the spotlights brandishing his sawn-off microphone stand, pausing only for an awe-struck boogie in front of Brian May. At the back, Roger Taylor's exaggerated drumming style meant that even the cheap seats could see his sticks held extravagantly high between beats. Deacon, dressed for comfort in a T-shirt and, in 1986, a pair of minuscule football shorts, was barely noticeable, nursing his Fender Precision bass stage right. When not performing, John favoured a bomber jacket or white sports coat, looking like an electronics expert from Leicester, which, of course, is exactly what he was. Magazine profiles of Queen from the time listed his favourite drink as tea;preferred meal? Cheese on toast. As Brian May once explained when discussing his colleague's diffidence: "John was never very impressed by things - that's his way."

Contrary to appearances, though, Deacon was no second banana. He didn't write that many songs on his own, but those he did include I Want To Break Free, You're My Best Friend and driven by his own predatory low-end jags, Another One Bites The Dust. Also, when it came to decisions regarding Queen's money, Deacon was no fool. "John keeps a very close eye on our business affairs," Mercury said. "The rest of the group won't do anything unless John says it's alright."

Away from the band, Deacon's musical acrivities were rather esoteric. While Mercury, Taylor and May all released solo albums, the bassist was handicapped by a total inability to sing. Instead, he worked on tracks by artists as diverse as Anita Dobson and Hot Chocolate's Errol Brown. In 1986 he contributed to the soundtrack for Biggles, a resoundingly poor film distinguished only by being Peter Cushing's final screen appearance. More bizarrely, in 1988, he appeared in two videos for Morris Minor And The Majors, a UK comedy rap act that parodied the Beastie Boys and were fronted by the comedian Tony Hawks.

"We met on Virgin Atlantic's inaugural flight to Miami," says Hawks. "John was a celebrity guest and Morris Minor And The Majors performed a comedy set on the plane. John loved it, so we all hung out together over a long and drunken weekend and a friendship was forged."

Hawks suggested that Deacon might like to have a walk-on part in the promo for their forthcoming single, Stutter Rap (No Sleep Till Bedtime). Deacon readily agreed, and can be seen in the video wearing a blue wig and gooning around with a guitar. "He was more than happy to look daft," says Hawks. "John struck me as someone who'd become a rock star by accident and may well have been happier doing something else, in spite of all the obvious benefits of fame and fortune. We remained friends for quite a few years, but as John became more reclusive we lost touch. I'd actually quite like to see him again."

BUT WHEN FREDDIE Mercury died in 1991, barring the following year's tribute concert, Deacon considered Queen to be at an end, went into retirement and largely seemed to withdraw from public life. He sporadically played bass on record and live with Taylor and May's separate projects, as well as being one of the occasional members of former Queen keyboard player Spike Edney's SAS Band. "I am mainly involved with looking after the childred at home," he said of his current activities back in 1996. Deacon ramains a dedicated family man, despite recent allegations in the Mail On Sunday of a friendship with a lap dancer four years ago. The bass player and his wife, Veronica, celebrated their 30th wedding anniversary in January this year and live in South-west London with their five sons and one daughter.

Deacon sightings are infrequent, and he is usually notable only by his absence. He was reportedly not present at Brian May and Anita Dobson's wedding in 2000, and shuns award ceremonies that honour his former band. Much to Deacon watchers' chagrin, a rumoured appearance on TV's Through The Keyhole turned out to be entirely without substance. In typically unpredictable fashion, though, John broke cover to attend a party for the internet gossip site Popbitch in 2001. In the same year, The Sun reported that he was displeased with the version of We Will Rock You( We Are The Champions), recorded with Robbie Williams for the movie A Knight's Tale. "I didn't want to be involved with it and I'm glad [that I wasn't]," he is alleged to have said. "I've heard what they did and it's rubbish."

Deacon exhibits a similar level of enthusiasm for other Queen projects, choosing not to involve himself in either the band's musical, We Will Rock You, or the reunion tour. Certainly, he doesn't need the money. Last year's sunday Times Rich List placed him 777th with 50 pounds million, a position he shares with Roger Taylor.

"John really has retired," said Taylor in 2003. "He doesn't like going out. He wrote us a letter in which he said, I fully endorse whatever you are doing and you have my wholehearted support but I don't want to be involved. John doesn't really enjoy other people's company."

On his website, Brian May was recently moved to pass comment. While fans speculated on the bassist's absence and as Queen 2005 gears up to go on the road with all the attendant media madness, May agreed the stoic presence of the man briefly known as Deacon John will be sorely missed.