M&S dress for Samantha Cameron

Samantha Cameron shows her appreciation of the speech

Samantha Cameron wore a Marks and Spencer dress while watching her husband's big speech to the Conservative Party conference.

The wife of the Tory leader sported a £65 grey dress with white spots.

Mr Cameron spoke of the couple's pain after the death of their son Ivan earlier this year and said his wife was the person who "sustains me most".

Mrs Cameron was one of a circle of people who advised the Tory leader on his conference address.

Unlike Sarah Brown, who introduced her husband before the prime minister's speech to the Labour conference, Samantha Cameron only took to the stage after the address when she embraced her husband.

'Proud'

While the prime minister's wife wore an abstract dress by designer Erdem Moralioglu for her appearance on the Labour conference stage last week, Mrs Cameron opted for a high street dress - voted "the best Marks and Spencer dress yet" by the Times in May.

It was part of a vintage-style collection sold by the retailer over the summer to celebrate its 125th anniversary.

Mrs Cameron has found her wardrobe under scrutiny this week and seems to have been choosing affordable clothes - wearing a Uniqlo sweater and Zara shoes earlier in the week.

She gave her husband the thumbs-up sign several times during the hour-long speech - which included several personal references, including one on the death in February of their six-year-old son Ivan, who suffered from cerebral palsy and epilepsy.

Mr Cameron said it seemed the world had stopped turning and and nothing else mattered, and said it was his wife who got him through.