What happened to Rod Stewart the songwriter?
The last original song the man behind global smash Maggie May released was the title track of 1998 album When We Were the New Boys. It was the only original on an album full of tracks written by other artists.
Since then, Stewart has concentrated on album after album of his Great American Songbook series and other cover collections.
"You could say we're addicted to it, really," he says in trademark raspy voice, made hoarser by a bout of flu.
"You could go on, I could record another five - we'd never run out of songs."
All of those cover albums to date - beginning with 2002's first Great American Songbook - have gone platinum in the UK and the US.
Stewart's fifth and final instalment of his lushly-orchestrated series features "good cocktail hour, dinner party music" including I Get A Kick Out Of You, I've Got You Under My Skin and Beyond The Sea.
Diehard Rod fans will lap it up. But don't they also deserve to know why the 65-year-old - who wrote such hits as You Wear It Well, Hot Legs, Baby Jane and Every Beat Of My Heart - has dried up when it comes to penning his own hits?
Stewart fires back a series of explanations.
"There's many reasons, I don't feel the desire at the moment - I haven't met somebody I feel I can write with.
"It's difficult to get the new material played with us old-timers, it really is.
"I think we've had a fair crack of the whip, so we can't complain.
"I wanna do a blues album, I wanna do a country album, so maybe after all that's done I can get someone to write with."
His most famed composition, 1971's Maggie May, propelled him to worldwide fame.
Although it was co-written with guitarist Martin Quittenton, Stewart says his memories of creating it begin with Ronnie Wood strumming Bob Dylan's 1965 song It's All Over Now, Baby Blue.
Wood, latterly a Rolling Stone, was Stewart's bandmate in The Faces.
"I think the first two chords may be similar, the melody's not," Stewart says.
"We did it at Lansdowne Studios in London and it was one of those where we went round the pub first and then saw what we got."
That's humble beginnings for a song which was originally the B-side to Reason to Believe before it was reclassified as the A-side thanks to public reaction. It went on to top the UK and US charts for five weeks each.
"When it went to number one in Britain and America, that's when we all went out and got drunk," Stewart says.
"The drinking went on for a long time and why not?"
He says he remembers visiting his parents shortly afterwards: "That was probably the most gratifying, more than any big cheque or new car or whatever, to know that not just my mum and dad but my whole family had stood by me.
"They weren't the type to say 'get yourself a day job, it's not going to last', which is not what you want to hear when you're a musician."
But will the former mod, who is due to become a father for the eighth time next year, ever again celebrate a self-written hit?
It's only when asked if he ever writes that things become clear.
"No, never. It's always been hard work.
"The nearest thing that this business I'm in comes to being a job is when I've had to write songs."
This is not an ageing rocker with a chronic case of writers' block. This is an ageing rocker who hates writing songs.
Stewart adds by way of a further admission: "Speak to anyone in The Faces, they'll say 'We had to lock him in a room and take the key away to get him to finish the lyrics to a song'.
"So it was always like being at school."
He continues: "When you think of the minimal amount of songs that I've written and how many of them have been successful, you could say I've got an impressive strike rate."
And while he hasn't completely ruled out a return to songwriting - "I wouldn't say that it'll never happen, it could happen" - don't hold your breath.
His coming out as a successful songwriter who detests writing songs marks him out as unusual.
But his success in recording long-established songs speaks for itself.
In the US, his last six albums have yielded two number ones, two number twos and two number fours.
And in album sales by British artists in America in the 2000s, he was outsold only by The Beatles and Coldplay.
Perhaps the real question is why would Rod Stewart bother to write another song?
Fly Me to the Moon...The Great American Songbook Volume V is out in the UK on Monday.