Tooth fairies in London are among the most generous in Britain, according to word-of-mouth by dentists.

They leave an average of �1.33 for each milk tooth left under the pillow.

That compares to a UK average of just over �1, a survey by the British Dental Health Foundation calculates. The �1 coin is the most common left by the Tooth Fairy.

“Children have around 20 milk teeth, so it’s no surprise Tooth fairies are so busy,” explains Dr Nigel Carter, the Health Foundation’s chief mouthpiece.

“Unfortunately, around one-in-three children are leaving teeth with signs of visible dental decay.”

The foundation has been promoting a National Smile Month campaign which runs until June 15 to encourage kids to clean their teeth every day and cut down on sweets and sugary drinks.

An estimated 15 million milk-teeth fall out each year, making an average of 42,000 ‘money drops’ a night, totalling well over �16 million a year.