A Cavalry Guard fainted on the Mall during a procession rehearsal today as a health alert was issued following tropical temperatures.

Pictures show the solider lying face down on the floor as he holds onto his rifle.

Temperatures rocketed to 25C across London at midday, according to the Met Office.

A yellow heat health alert has been issued by the UK Health Security Agency (UKHSA) and Met Office for most of England.

A Cavalry Guard fainted on the Mall today during a procession rehearsal as a health alert is issued following surging temperaturesGetty

It comes as forecasters suggest temperatures could peak at 32C in parts of the UK by Thursday.

A procession rehearsal was carried out today ahead of a state visit by the Emperor and Empress of Japan later this week.

Weather experts warn of a likely "increase in mortality across the population" from today until Thursday.