"What are you doing here?", asks Seagoon. Quick as a flash - and atypical of Spike Milligan's wit - Eccles replies: "Everybody's gotta be somewhere."
He had a point. There was a reason why an 18-year-old Elvis Presley walked into 706 Union Avenue in Memphis - Sun Records - one day in August 1953 and recorded My Happiness and That's When Your Heartaches Begin for his mother's birthday.
Likewise there was a reason Paul McCartney, aged 15, went along to the summer garden fête of St. Peter's Church in Woolton, Liverpool, in July 1957, where he was invited by John Lennon to play on stage with his band, The Quarrymen.
Another moment, and one that also changed the course of popular music, occurred on the morning of October 17, 1961 when teenagers Mick Jagger and Keith Richards ran into each other on Platform 2 of Dartford railway station. Growing up around the corner from each other in Dartford, a London suburb on the Kent stretches of the Thames Estuary, they had been primary school classmates some years before. On the ensuing train journey to London, however, they discovered a shared love of American blues music.
This was the 'genesis moment' that lead to the formation of "The Greatest Rock'n'Roll Band In The World". No idle boast that, but one with little contention. You can debate the relative merits of The Beatles, The Who, Led Zeppelin, Queen, Pink Floyd, The Clash, the Sex Pistols, Nirvana, U2 - take your pick of anyone else - but there is, arguably, no one else who has been able to encompass all that "rock and roll" entails, musically or in any other application.
At the time of their suburban railway encounter, Jagger and Richards were anything but rock'n'roll: the former was studying at the London School of Economics, the latter attending Sidcup College of Art, just down the road from Dartford. When Jagger invited Richards to join his fledgling R'n'B outfit, Little Boy Blue & The Blue Boys, the course of rock history was set. Over the coming months the pair became fixtures of the London music scene, eventually forming a new group with lead guitarist Brian Jones, a babe magnet from Cheltenham whom they'd met in the Bricklayer's Arms pub in Soho, along with keyboard player Ian Stewart and drummer Mick Avory (later to join The Kinks).
50 years ago tonight, on Thursday, July 12, 1962, the group - now named after Muddy Waters' Rollin' Stone - were invited to fill in for British blues legend Alexis Korner at London's Marquee Club, then on Oxford Street, while Korner's Blues Incorporated were doing a radio show elsewhere. And thus The Rolling Stones came into being.
1962 was clearly a fertile time: The Beatles were in Hamburg honing their thing; a 17-year-old Eric Clapton bought his first electric guitar in Bell's Music of Tolworth, Surrey; other legends were in embryonic form, such as The Who's Pete Townshend and John Entwhistle putting together a trad jazz band called The Confederates.
In the London suburbs, something was happening. Pop's shackles had been loosened by Elvis and his provocative hip-swinging, but in 1962 Britain, it was the blues, R'n'B and soul music that was taking a hold of suburban teenagers.
Hair was getting dangerously collar-length, and the electric guitar was becoming as much a symbol of rebellion as the AK47 is a symbol of terror today.
Within a few months of their Marquee debut, the Rolling Stones had established themselves as the stars of the Crawdaddy Club, a Sunday afternoon blues residency at the Station Hotel in Richmond-upon-Thames. By January 1963 the band's 'classic' line-up was complete, with Charlie Watts joining from Blues Incorporated, and former RAF motor transport clerk Bill Wyman taking over on bass. It was to be a line-up that would go on to endure the rough-and-tumble of rock star brotherhood, losing Jones to misadventure in 1969, Wyman to boredom in 1992, and at various times, Jagger and Richards - The Glimmer Twins - to their own fraternal abrasion.
Half a century after their live debut, the Rolling Stones still represent their own piece of fabric, their own unique hereditary tartan, in the pantheon of popular music. Half a century on, they remain a powerful currency.
That mouth-and-tongue logo - as distinct as the golden arches of McDonald's, as representative of incorrectness as the Playboy bunny - is not only an iconic brand, but one which represents a combination of fantastic music and the debauchery of a true rock'n'roll lifestyle. It may have become somewhat faded as a fashion brand, but hey, people still wear Paco Rabane.
The Rolling Stones are an industry, carefully managed as any corporation, with annual company meetings taking place at the Amstel Hotel in Amsterdam (quite what should bring this of all bands to Amsterdam....), and a corporate marketing presence as active today as any other commercial venture, with pages on Facebook, Twitter, Pininterest, Tumblr and probably LinkedIn. Hardly a band contemplating retirement.
"There might be life in the old dog yet - we'll die gracefully, elegantly wasted," Richards has told the BBC this week, confirming that they may be preparing for a long-rumoured 50th anniversary tour. "There's things in the works - I think it's definitely happening. But when? I can't say yet."
The creative zenith of Exile On Main Street, Beggars Banquet, Let It Bleed, Sticky Fingers and Some Girls may have long since past, but I doubt anyone really cares. A Stones concert today (I last saw them in 2007 on their excellent Bigger Bang tour) will still combine the jukebox predictability of standards their ticket-buying patrons expect to hear - Jumping' Jack Flash, Satisfaction, Brown Sugar, Honky Tonk Woman - along with a few random selections from the 29 studio albums they've recorded since their eponymous debut LP (a collection of mostly blues covers). And, yes, they'll always let Keith sing one, if only to allow him to trot out his "It's great to be here! It's great to be anywhere!" gag, which has over recent years turned into a catchphrase much like Bruce Forsyth's "Nice to be here, to be here nice!".
The Stones don't even need to be considered fashionable: every time they've gone on tour in recent years - actually, in the last 30 years - they have prompted a flood of guff about whether they should just retire. I've long argued that bands should go on as long as they're enjoying themselves and their fans are enjoying themselves with it.
I've seen BB King play at the age of 83 and put on a storming show, so with Jagger and Richards a year shy of their 70th birthdays (and who'd have thought you'd see that written about Keith...), Charlie Watts now 71 and their 'kid brother' Ron Wood carrying on like he wasn't 65, the Stones have got some way to go before they catch up with their musical heroes. And in any case, this band has long since passed the stage of looking embarrassing. They are, after all, the Rolling Stones.