Is chewing food 50 times the tip that keeps SamCam slim?

Your grandmother might have told you to chew every mouthful of food at least 100 times to stay healthy.

It seems that Samantha Cameron is a fan of the method, although she may not take the advice to such extremes.

The wife of the former prime minister revealed that she chews every mouthful up to 50 times.

Mrs Cameron, 46, is believed to be a devotee of the Mayr principle – which focuses on smart eating to get a healthy gut and stay slim.

Her father, Sir Reginald Sheffield, has been known to attend the exclusive Viva Mayr Clinic in Austria at least once a year.

Patients are given just half an avocado for a meal and instructed by doctors to chew each bite at least 30 times.

The clinic, founded by physician Dr Franz Mayr, opened a centre in London’s Harley Street this year – the first outside of Austria. It is known for its strict regime that ‘purges toxins’.

The wife of David Cameron was said to ‘sometimes subscribe’ to the clinic’s principles in an interview with a Sunday magazine.

She also revealed that she feared being seen merely as a politician’s meek spouse while living at No 10 because she could not talk to journalists.

She said: ‘I’m very opinionated and argumentative, especially when it comes to Style: Samantha Cameron politics ... I worried everyone would think I was this weird Stepford Wife as I never spoke.’

Mrs Cameron dispelled long-running claims she had been a ‘wild child’ during her youth in Bristol – and confessed to having voted for the Greens ahead of her Tory husband’s party.

The mother of three told the Sunday Telegraph’s Stella magazine: ‘I didn’t always vote Conservative ... sometimes I went Green.’

Mr Cameron has previously revealed how she had supported Greenpeace and Friends of the Earth when they first started dating.

Since leaving Downing Street a year ago, Mrs Cameron launched her own fashion label after previously putting her career on the backburner while her husband was in frontline politics. The Mayr Centre and a spokesman for Mrs Cameron were approached for comment yesterday.

Liberal Democrat leader Sir Vince Cable has revealed he visits his first wife’s grave with his current partner.

Sir Vince lost his wife Olympia to cancer 16 years ago and married Rachel in 2004.

The 74-year-old said his second spouse had encouraged him to visit Olympia’s grave to calm his nerves on election day this year as he waited to hear if he had won back his Twickenham seat. He said: ‘Ever since we met, Rachel has been hugely generous in spirit. She’s been lovely about it and sometimes comes with me.’