Rod Stewart is on Parky as I type. I'm not a fan. I think he's overrated. Fair's fair: he's realised that he's getting on a bit and needs to find a new sound. For a while, he tried to be Tom Waits (how the hell did he have such a massive hit with Tom Traubert's Blues, when he'd totally ruined it?). Now he's trying to be Harry Nilsson. I don't like his sound, but good luck to him.
Rod Stewart did one very wonderful thing: he sung (uncredited) lead vocals on Python Lee Jackson's masterpiece, In a Broken Dream: a genuine classic. And what happens to genuine classics? Some arsehole does a cover version of them and totally ruins them. In this case, the arsehole was Ronan Keating. Enough said.
Now you know how it feels, Rod. Stop ruining other people's songs and write some of your own: you're up to it (I think).