The couple hope to raise more than �10,000 for charity

Katie Austin and Gordon Fryer, dressed in bridal gown and morning suit, will wed halfway round the 26-mile route.

Keen to keep up momentum, the couple from Southampton will make a brief stop for vows and a toast on Tower Bridge.

Ms Austin, 25, said: "The day is so highly charged for all runners, but for us, getting married in the middle will give us an even bigger boost."

She said she hoped the high of getting married would help her through the pain barrier in the second half.

This one will be quite special I think June Lewis, registrar

"We had already signed up for the London Marathon when we got engaged, so originally we were trying to work out a way of fitting the wedding around it.

"But then we decided we could do both at the same time," she said.

Katie's parents will also be running the marathon and will be witnesses at the ceremony.

It will be conducted by Southwark registrar June Lewis for whom the service will be the last in her 17-year career.

"I have married a couple during the marathon before, but they weren't runners, just spectators. This one will be quite special I think," said Ms Lewis.