I'm the OLDEST WOMAN Rod's ever SLEPT with!

Justice-seeker, menopause campaigner, police officer, TV host, mum-of-two and wife of rock royalty - step forward, Penny Lancaster

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Have you ever tried it?' asks Penny Lancaster, raising an eyebrow. We are in a quaint book-lined meeting room at publisher Bloomsbury's central London HQ discussing her memoir, Someone Like Me, which in chapter five charts the beginning of her relationship with singer Sir Rod Stewart - including their first-ever intimate moment.

It was summer 1999 and during a tour of Rod's Victorian Pre-Raphaelite art collection at his home in Essex. While Penny momentarily reclined on his fourposter bed, the rock icon leant down for a lingering 'upside-down kiss', which, she writes, turned her 'whole body' to jelly.

'It still works to this day,' she grins. 'We're so used to kissing in the same manner, so if you turn it around like that, it feels like the first time you've been kissed all over again.'

This year Rod turned 80, and Penny - now 54 - is the same age he was when she started dating him at just 28.

'The thing I think of is, I'm the oldest woman Rod's ever slept with - and that happened a long time ago,' laughs Penny. 'When I met him, the oldest woman he'd ever slept with would have been 30. Now he's the oldest man that I've slept with too!'

Is intimacy still as important now as it was back in the day?

'Oh gosh, it's still so important,' she replies. 'Just simple hugs and touches, and looking into each other's eyes.'

As parents to two boys, Alastair, 19, and Aiden, 14, plus three dogs, and with homes in Essex, LA, Florida and France, Penny and Rod's story is the stuff of dreams.

But in the early days, when Rod was a dad of six with four different women - including ex-wives model Rachel Hunter, 56, and actor Alana Stewart, 80 - Penny had no faith in them having a future together.

'My biggest burning desire was to have a family. I respected that he had been through that enough times, and that might not be where he would want to go again.