A year later came "Judy Teen", a quirky, three-minute slice of surrealism that soared straight into the singles charts on the back of a pizzicato violin melody and swooning chorus, followed by the equally curious "Mr Soft", which sounded as if someone had thrown fairground music into the embers of Hunky Dory.
Adopting a glamorous persona inspired as much by A Clockwork Orange as by Bowie, Harley became a big star. He thrived on a love-hate relationship with the music press, which he manipulated with a skill honed during a brief previous career as a journalist, his Wildean proclamations of his own genius earning him a reputation for egotism and arrogance, which he milked for more headlines. "I never meant to be arrogant; just honest," he apologises today.
The prevailing opinion of Harley as an arrogant young pup was reinforced when all but one of his band walked out on him in the middle of a sell-out tour in 1974. He defiantly announced that he would bounce back with an even better one. True to his word, he did just that (first adding his name to the top of the marquee as "Steve Harley and Cockney Rebel" and then adding a guitarist) and proved the point when their first single, "Make Me Smile (Come Up And See Me)" gave him his first number one, in 1975.
Now, at the age of 54, Harley combines a thriving solo career - he still plays more than 100 dates a year - with a job presenting Sounds of the Seventies on Radio 2. We meet across the road from Broadcasting House. For his new album (The Quality of Mercy) and a 55-date tour, Harley has reinstated the name Cockney Rebel for the first time since the Seventies.
Born and raised in south London, Harley was dominated by ill-health after he was struck down in the polio epidemic of 1953 when he was only two. "I wasn't hit badly but it changed my life," he says. He spent three-and-a-half years in hospital between the ages of three and 16, including two spells of almost a year. "I am solitary as a result," he says. Having shied from discussing his illness during his heyday, he has belatedly addressed it in a moving new song, "The Last Feast". "It's a primal scream," he says. "I remember pain beyond description after the surgery and I knew I was at the very brink of human tolerance and all the morphine in the world would not ease it. For a long time my life was in a bedside cabinet and it was a notebook and pen, all words, words, words. And I read voraciously. At 15, I was reading Hemingway and Steinbeck and the poetry of DH Lawrence and TS Eliot with an insatiable appetite." He still carries Eliot's collected works with him at all times, saying: "I couldn't live without it."
After the success of Cockney Rebel, Harley fell victim to the traditional pitfalls of pop and fortune. "I put four-fifths of my income from 1975-79 up my nose," he admits. "And the rest I put down my throat in the shape of Remy Martin. Marc Bolan was my mate and it was all cocaine and cognac, night after night, but luckily I never did the hard stuff - hypodermics have always frightened me."
Towards the end of the decade he moved to Los Angeles but did not settle. "I did a lot of brunch," he recalls. "but I didn't write a single song." Returning to Britain, he met a Scottish air hostess and fell in love at first sight. They are still together today and have two children. Parenthood brought an end to his drink-and-drug-fuelled lifestyle.
For much of the Eighties, Harley's priority was parenthood, but he came out of semi-retirement to sing a duet with Sarah Brightman for a then-unstaged Andrew Lloyd Webber musical. "The Phantom Of The Opera" put him back in the top 10 and revived his career to such an extent that he was offered - and took - the lead role in the West End production. But, after three months of rehearsals with the producer, Hal Prince, he was replaced by Michael Crawford. "What happened is something of a mystery to me," he says, and it clearly still rankles. What he will admit is that the legacy of his polio, which left him with a limp, caused doubts about his ability with the physical rigours of the part.
Harley is looking forward to his biggest tour in decades with renewed optimism. "I have got five ideas to everyone else's one. I am not going to stand in the corner with nothing to say."
Steve Harley tours to 9 December (www.steveharley.com); 'The Quality of Mercy' is on Gott DiscsReuse content