Janet Barrett was confused when the item, dated Nov 29 1919, dropped through the letterbox at her guesthouse in Weymouth, Dorset.

A note from the Royal Mail, apologising for any delay, accompanied the delivery.

Mrs Barrett, 56, said she hoped somebody would recognise the name of the addressee, Percy Bateman, and shed some light on the mystery.

She said:"When I first looked at it I wondered why I had been sent this tiny envelope. Then I looked closer and spotted the date, 1919.

"I could not believe it. Who knows where it has been all these years?"