As she finished – slightly disappointed – in 1,644th place, boyfriend Nathan Roulson handed her three red roses, went down on one knee and proposed.

Cheers erupted from the crowd as a shocked but delighted Joanne said yes and Nathan placed a hand-made diamond and platinum engagement ring on her finger.

Nathan, 33, had been planning the public proposal for three months and had already been interviewed over the tannoy by race officials.

Joanne, 30, a human resources manager for an investment bank, was still running the 10-kilometre course through the city streets and had no idea what was going on.

The couple, who are members of Halstead Road Runners, both entered the race along with around 15,000 other competitors. He finished 460th.

They had decided to combine it with a visit to an old schoolfriend of Nathan's who lives in Sweden.

Nathan, a design engineer for Ford, said: "I'd been thinking about asking Joanne to marry me for several months but I wanted to do something different. I really wanted to make it a surprise and I was more than happy to make a public statement about how I feel about her. Once she accepted the ring and we kissed, the crowds cheered."

Joanne and Nathan, of Halstead, went to Ramsey School but didn't get to know each other well until less than two years ago.

"She had done a little bit of running before we met," said Nathan race director for the Halstead Marathon. Now the couple are both keen competitors.

They have not named a wedding day but have another important date in their diaries. They have entered the London Marathon to raise money for the Stroke Association, after Joanne's father died earlier this year.