It’s the Birmingham poster which inspired millions of teenage male fantasies, a racy stroke of genius which has become as much a part of UK culture as that long, hot summer of 1976 when it was first taken, the flying pickets, punk rock and the flares.

It’s often said that the 70s were the decade that style forgot, and that may very well be the case when we consider the clothes, Johnny Rotten, his ghastly sidekick Sid Vicious, and the mullets, but photographer Martin Elliot’s picture of his girlfriend Fiona in tennis gear has effortlessly transcended time and fashion.

The famous photograph snapped on a Birmingham University tennis court went on to become the biggest selling poster image of all time, shifting over two million copies worldwide.

The sales figures speak for themselves. The shot of the tennis girl from Birmingham is right up there with photographic images of all the greats across a span of cultures, from JFK to Martin Luther King, Jagger to Lennon, David Bailey to Annie Leibovitz.

For as long as teenage boys have fantasies, Fiona Butler’s rear will be up there with the likes of Brigitte Bardot, Sophia Loren and Marilyn Monroe. They may be more famous, but Fiona and her backside sold more posters, so Martin Eliot must have struck a chord or two with his Edgbaston handiwork back in 76.

With the poster back in the news now that the original dress and racquet are being sold at auction by Stourbridge auctioneers Fieldings, it’s timely to consider why the Tennis Girl has lasted so long, why millions handed over hard-earned cash to buy a copy.

I’m neither a tennis fan nor an expert in photography, but it seems to me that Martin Elliot’s image has stood the test of time largely because it appeals to the imagination as much as anything else. It’s suggestive but not explicit, conceals more than it reveals and we never get to see the girl’s face, ensuring an air of mystery. But it’s moot to consider whether Fiona Butler’s rear view would have endured as long if the photograph had been taken in 2014.

The Swinging Sixties had given us Oh Calcutta!, so-called free love and the pill, while the 70s came up with Carry On films, Jackie Collins, Harold Robbins and all the rest. But it’s all pretty tame compared to today’s minefield of explicit sexual imagery and internet porn.

Look at Miley Cyrus and her antics, and the hordes of impressionable teenage girls who flock to her concerts. Look at a so-called star of TV like Jonathan Ross who thought it was clever to ask David Cameron if he had ever had schoolboy sexual fantasies over MrsThatcher. Subtle stuff, Wossy – you really earned your £6 million a year on that one.

Look at the likes of Richard Desmond, who made a fortune from his porn empire but was still allowed to buy one of Britain’s most famous newspaper titles, the Daily Express.

But it’s not all about sex. Nothing is left to the imagination now, nobody is immune from abuse in today’s Roman-style Colosseum of the cyber age, no subject too sacred for the trolls, no indignity worth rejecting if you can get your name up in lights and earn an extra buck or two.

The World Cup has been depressing enough for England fans without the sight of young Daniel Sturridge appearing in a TV advert for some fast food joint. But young Daniel is only meekly following the nauseous example of ‘Goldenballs’ Beckham, whose Croesus-style riches didn’t stop him prostrating himself in his underwear like some sleazy porn star. At least Sturridge keeps his clothes on in his burger promotion.

The noble art of comedy has suffered more than most from this obsession with brazen exhibitionism and dubious bad taste. Like the Tennis Girl poster, the best comedy material was always clever and subtle, from the glories of Dad’s Army – nobody lampooned the often absurd nature of authority figures a la Captain Mainwaring as well as Jimmy Perry and David Croft – to the madcap chaos of Fawlty Towers.

It’s arguable if the TV script commissioners of today would allow John Cleese and Connie Booth to create the Major, a blimpishly blatant racist who also happened to be one of the great comedy creations of all time. We might never have seen the Major attempt to shoot Basil the Rat or object to German guests if Cleese were dreaming him up today.

Cleese’s Major was a product of an age when racism was rife, but his buffoonery accurately reflected a mindset that has thankfully been consigned to the margins. But race is much more of a minefield now than it was back then. Porridge, the Two Ronnies, Only Fools and Horses, Ken Dodd and his flights of fancy, the wholesome slapstick of Morecambe and Wise – they are all timeless to a large degree, relying on wit and suggestion rather than shouty abuse and hate-filled vitriol.

But now a so-called comedian called Frankie Boyle thinks he’s amusing by suggesting that Olympic heroine Rebecca Adlington has a face like the reflection in a spoon. It’s hardly up there in the ‘Don’t Tell ‘em, Pike’ stakes for ingenuity and wit, is it?

It’s weirdly ironic that the comedians of today continually tread on eggshells over race and other sensitive issues at a time when personal abuse and sledgehammer-style loudmouth tactics are often the stock on trade of many of the very same performers.

But you don’t need a sledgehammer to crack a nut. Subtlety and ingenuity will always endure, and the late Martin Elliot’s photograph of the Tennis Girl illustrates that timeless maxim perfectly in an age when we are often pressurised into revealing all to the watching world, whether we particularly want to or not.