Its hipster appeal has seen it appear on menus around Britain in recent years.

But now, kale has emerged as the healthy leaf of choice not just for people - but for ducks.

The Canal and River Trust, which is campaigning for people to feed ducks with lettuce leaves rather than ‘junk food’ bread, said it had carried out aLettuce Taste Test to find out whether the birds “favoured one type of leaf over another”.

Kale – which was included as a “wildcard” despite actually being a cabbage – proved to be “the biggest hit”, according to the results of the rudimentary testing carried out by the charity on Aylesbury’s Grand Union Canal.

The vegetable, which the trust noted was “currently gracing the table of many trendy restaurants” was given a “duck approval rating” of 10/10 by the trust’s testers after they observed that “ducks couldn’t get enough” of it.

It proved far more popular than the humble iceberg lettuce, which scored just 6/10 after testing found the ducks “had a nibble but didn’t go back for seconds”.