In 1920s Britain it was a popular fast food and often the only green veg available to help protect the nation from winter colds and flu.

But watercress has fallen out of favour among young people and is seen as a dowdy alternative to its trendy rivals kale and spinach.

Just five per cent of under 28s now buy watercress, compared to 41 per cent of 35 to 54 year olds, Kantar Worldpanel data shows.

Growers, alarmed that teenagers and young professionals are snubbing their produce, have decided to fight back with an image makeover for the leafy green.

A new Instagram campaign taglined #watercresschallenge is urging young people to "chop it, blitz it, toss it and wear it."

Tempting watercress recipes include a James Bond-style cocktail good for hangovers, a vibrant green "power ball"; energy snack instead of a caffeine kick at work, and for those still wary about eating the veg a suggestion to use it on the face as a beauty aide.