'SamCam' secret weapon is unveiled as party rivals launch their war of the wives

Samantha Cameron may work for the exclusive Smythson fashion house but has shown a keen awareness of the public mood. Mrs Cameron wore high street fashion and trainers during a visit to the Caring for Life charity, at Crag House Farm, in Leeds, which provides residential housing for homeless people and runs a variety of activities and projects.

Her main competition for down-to-earth style, Gordon Brown's wife Sarah, also hit the election trail yesterday with a low key 35 M&S denim pencil skirt, pink Banana Republic top, fitted blazer from Laden Warehouse, Brick Lane, and pink pumps from Stuart Weitzman.

Mrs Cameron then visited a village hall in Burringham, near Scunthorpe, after a brief stop at the Thealby Hall home of father, Sir Reginald Sheffield, owner of a 3,000-acre Lincolnshire estate.

Although Mrs Cameron, dubbed SamCam, refused to comment on whether she was campaigning, it is clear she represents a big part of her husband's quest for power.

She is seen as crucial for him to win the votes of mothers.

Mr Cameron denied she was a "cosy photo opportunity" saying: "Samantha said to me that as well as being a wonderful wife and a very brilliant mother and also very good at her own business, she said she wanted to help me during the campaign and one of the things she's most interested in is the social action projects."