An Army sergeant will take on the Virgin Money London Marathon wearing a suit of armour - as a heatwave is forecast.
Paul Beddows, 33, is fundraising for the Armed Forces charity SSAFA and is trying to break the current Guinness World Record for the "fastest marathon in a suit of armour".
The current record, of six hours 46 minutes 59 seconds, was set at the HC Andersen Marathon in Denmark in 2008.
Sgt Beddows' suit of armour weighs 35kg and, according to the Met Office, temperatures could reach 20C on race day on Sunday.
"It seemed like a brilliant idea at the time, but now the realities are sinking in," said Sgt Beddows, of Sawtry, Cambridgeshire. "I can't just slip the armour on and head out by myself, I need help to get into it, and nearly every step I take in it hurts.
"But I have no doubt that I will finish the marathon - and am quietly confident that I'll have a good chance of breaking the record too."
Sgt Beddows, who has worked in the Intelligence Corps since 2004, has previously completed four long-distance Ironman triathlons.