It is the hottest Spring in living memory.

But that hasn’t stopped train bosses from pumping heat through their sweltering carriages.

First Capital Connect has confirmed its vehicles, some of which are 20-years-old, do not have simple on-board thermostats to control temperature.

Thousands travelling on the Brighton to London mainline have been blasted with hot air while outside conditions exceeded 20C.

Following a number of complaints the firm stated it will switch off the heating on all its trains, promising its new fleet of trains would be better equipped.