An Oxford man nicknamed the "grandfather of British charity" was surprised with a lifetime achievement award by Victoria Beckham and a television crew in London last week.

Joe Mitty, 87, has won a Pride of Britain award to recognise more than half a century of work for Oxfam, in Broad Street, where he started as the shop's first ever employee in 1949.

Oxfam's longest-serving employee thought he was taking part in a documentary at the Notting Hill branch when Victoria Beckham handed him an invitation to receive the honour at a televised ceremony tonight.

Mr Mitty, of Cumnor, said: "I was stunned. I was lost for words for several minutes. But it's not an award for myself. It's for me to share with the Oxfam staff, who are all enormously valuable to the charity."

Mrs Beckham said: "When I heard what Joe has done, I was amazed. He's an incredible man and very deserving of this award."

A panel of celebrity judges, including Dame Kelly Holmes, TV presenter Sharon Osbourne and GMTV's Fiona Phillips, will present the prizes, with some of Britain's biggest names in the audience, including Prince Charles, Prime Minister Tony Blair, Jude Law, David Beckham and Rod Stewart.

Oxfam staff nominated Mr Mitty for his dedication to the charity over 57 years, which has seen it grow from a single shop making £500 a year to a £82.3m enterprise, run by 21,000 volunteers in 750 shops nationwide.

He was working as a civil servant when he saw an administrative secretary job advertised by Oxfam.

Mr Mitty said: "I was blessed to join Oxfam when I did. It has been a journey of hope.

"Back then the shop was in need of a bit of TLC. I realised that here was something that could flourish and we doubled the profits in the first year."

"What has really made the shops successful is Oxfam's incredibly talented, hardworking volunteers."

Mr Mitty's sales techniques have made money for Oxfam from some unusual goods, including a 30ft houseboat and a donkey tethered to the shop door.

Pete Orrey, Oxfam's business analyst, said: "Joe is an inspiring guy to work with. He's a great communicator of Oxfam's spirit."

Twenty other unsung heroes will be presented with prizes at the annual Pride of Britain awards, hosted by Carol Vorderman.

The event will be shown on ITV at 9pm tomorrow.