The 26-mile event takes place on Sunday, April 22, with Alan celebrating his 21st birthday a week later.

A knee injury curtailed his training for more than a month, but he has now resumed his battle to pound the tarmac.

Israel-born Alan, who was brought up in South Africa and later moved to Prestwich, told the Jewish Telegraph: "It has been something I have wanted to do for a while.

"I was volunteering with Magen David Adom in Israel in the summer and another volunteer from London, Alex Miller, told me she had signed up to take part in the marathon for Emunah.

"She told me they had a spare place, and, as I know it is difficult to secure a place without having to go through a ballot, I decided to sign up without hesitation."

Alan is hoping to rise between £1,500 and £2,000 for Emunah, a charity which helps thousands of children in Israel.

Alan, the son of Heidi and Martin Greenstein, said: "I am doing my final year at university and am really busy, but I thought I may not have the chance again. Emunah is an amazing charity, as well."

The former King David High School pupil, who is reading medical biochemistry at the University of Leeds, suffered a blow in November when he contracted iliotibial band syndrome, a painful knee ligament injury.

He added: "I was forced to stop training for five to six weeks and only started again three weeks ago. I am still in a bit of pain, but I play for the university rugby team and swim too, so I am managing the best I can.

Alan has been running 50-60 kilometres a week and is hoping to finish the marathon in just under four hours.

To donate, visit: www.justgiving.com/alan-greenstein