The two stars had a brief relationship in 1973 at the same time as Rod was recording his fifth solo album and their romance had a profound and lasting effect on the singer's music.
Rod recorded a cover version of Bob Dylan's 'Girl from the North Country' for his LP, which was one of Joanna's favourite songs and she was one of the first people he ever played it to.
Former model Joanna, now 71, told the Daily Express newspaper: ''When I was in my late twenties I went out with Rod Stewart for about 20 minutes ... I remember him pitching up early one morning about four o'clock. He had this track and said, 'This is for you.' It was 'Girl from the North Country' and I adore Bob Dylan. To hear Rod singing this fabulous song in his gravelly voice touched me so much.
''I've studied the album and it doesn't say dedicated to Joanna Lumley so you've only got my word for it. I could be lying!''
Joanna - who has been married to conductor Stephen Barlow for 30 years - admits dating Rod, 73, was very exciting because he was an extravagant rock 'n' roll star.
But as well as being a larger than life character, the 'Absolutely Fabulous' actress insists Rod - who is now happily married to Lady Penny Lancaster - was also a very kind man.
Joanna revealed: ''He was so fabulous. He had done 'Maggie May' and it was the time that he still wore pink satin suits and drove a Lamborghini and was glamorous ... He would say things like, 'Come to Marbella I want to buy a yacht,' but he did sweet things too. My son was at school and he'd stand by the gates to pick him up. Other mums would be fainting flat on the ground.''
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