1. ITV Report

London basks in hottest April day for nearly 70 years

London is baking in the hottest April day since 1949, triggering warnings for London Marathon runners amid predictions Sunday's race could be the warmest on record.

People enjoy the hot weather on Richmond riverside

Temperatures soared to 29.1C in St James's Park making it the warmest April day for 69 years.

People enjoy the hot weather on Richmond riverside
People canoe along the River Thames in Richmond

And the mercury could hit 23C in the capital on Sunday, prompting marathon organisers to add more water, ice and shower stations along the 26.2-mile route.

Conditions may be especially difficult for fancy-dress runners, including the almost 100 attempting Guinness World Records dressed in outfits like a suit of armour, a Paddington Bear costume and ski boots.

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Regular runners are being advised to consider dropping their goal-times and run more slowly.

The hottest London marathon on record was 22.7C (72.9F) in 1996.

The start of the 1996 London Marathon at Blackheath

Most importantly, runners should adjust their goal for Sunday and plan to run at a slower pace. If they were planning to run in fancy dress, they should think carefully if that is appropriate in the forecast conditions. We want to stress that there will be plenty of water available and runners should drink according to their thirst and use spare water to douse their head and neck.

– Hugh Brasher, Marathon event director