Tanni Grey-Thompson: Eleventh London Marathon

Their plan is to start the race, then meet up with family and friends at Tower Bridge, and be married by a friend of theirs - a bishop in full regalia.

The newly-weds will then complete the race alongside more than 26,000 runners on the 21st anniversary of the event.

The pair are making their wedding vows on the run to raise money for the Welsh cancer charity Tenovus.

The couple have a history of marking family events in unusual ways.

Nigel proposed to Angela on TV's Trisha's Show, and their first child Ellie was christened on Snowdon by the same Bishop, who was then a reverend in what is believed to have been the highest altitude christening in Wales.

Wheelchair athlete

The pair will be running alongside golden Olympian Sir Steve Redgrave who is competing along with his wife in the marathon for the first time after giving up rowing.

Nigel and Angela are not the first to get married during the annual event.

Croydon couple Mick Gambrill, 46, and Barbara Cole, 43, pipped them to the post in 1999.

Wearing custom-made wedding outfits designed by Jeff Banks, the couple will stopped off at Charlton House, near Greenwich, south London, where they were married by a registrar before going on to complete the race.

This year's race has its fair share of familiar Welsh faces.

Cardiff wheelchair athlete Tanni Grey-Thompson is taking part in her 11th London Marathon.

Grey-Thompson - the winner of eight Olympic golds - was hoping to do better than she did last year.

Then a puncture took more than 10 minutes off her time.