For most people running the London Marathon is a tough enough challenge in itself, but for brothers Chris and Joe Carter the 26-mile test of endurance will be one of seven races they are going to run in seven days.

The brothers will be running through the capital on April 21 having already covered six separate marathons from Bournemouth to Richmond.

Chris, 27, from England’s Lane, Belsize, and Joe, 24, from Tooting, are raising money for Prostate Cancer UK.

Their cause has added poignancy after news just weeks ago that the brothers’ uncle had been diagnosed with the disease.

Chris is a fundraiser for the charity and had been planning the challenge long before his uncle’s diagnosis.

He said: “Having one of my own family diagnosed made me take a step back and really look at my work.

“It’s been so cold training for the marathons and it’s given us a real second wind knowing that what we are doing is going to help one of the family. It definitely brings it closer to home.”

The brothers will begin their challenge by running in Bournemouth on Monday, followed by the New Forest Marathon, the Brighton Marathon, the Sussex Marathon and Richmond Park next Friday.

They will then run the Royal Parks Half-Marathon through London twice on the Saturday before the London Marathon on Sunday.

The brothers aim to raise £4,200 for Prostate Cancer UK and so far have more than £3,500.

Husband and wife team Lauren and Jonathan Barr will also be at the London Marathon start line with the Carters.

Mr Barr, 53, a partner in Hampstead Garden Suburb estate agents Godfrey and Barr, will be competing in his fourth London Marathon while Mrs Barr, 48, will be tackling it for a third time.

They have so far raised £4,000 for North London Hospice.

Mr Barr, a former Suburb resident, said: “It will be fantastic if we can go over the line together.”

To sponsor the Barrs, visit www.justgiving.com/LaurenandJonathanBarr. To sponsor the Carter brothers, visit uk.virginmoneygiving.com/team/CarterBrothers