Prime Minister David Cameron is one of the artists who have contributed to a secret charity postcard art sale being held this month.

Postcards painted by artists, schoolchildren, footballers and celebrities including quiz show host Bradley Walsh will be sold on July 8-9, raising money for Bromley’s Freddie Farmer Foundation.

Although each one will be signed on the reverse, buyers won’t find out which artist is behind their postcard until after the sale has closed.

52 postcards will be up for grabs.

The miniature art sale has been organised by Barbara Gordon from Swanley Road, Welling, to raise funds for equipment that will help disabled children to walk.

Organiser Mrs Gordon said: “This is a wonderful opportunity for us to raise awareness of the important work the Freddie Farmer Foundation does for disabled children.”

Postcards will be on sale for the bargain price of £5.

The art sale at Sainsburys on Stadium Way, Crayford will begin on Friday 8 July at 10am.

The Freddie Farmer physiotherapy centre is one of a handful of independent UK therapy centres offering specialist equipment and therapeutic exercises, supporting disabled children from all over London and the South-east.