A firm of estate agents has received a “return to sender” letter 40 years after it was posted.

The letter, postmarked August 21, 1975, finally made it back to the Halford Street office of Harrison Murray in Leicester.

The envelope bears the Harrison Murray logo of the time, along with a printed address to The Occupier of 100 Roman Bank in Stamford, Lincolnshire.

The typed letter, on Harrison Murray letterhead, contains details of a proposed redevelopment of the Stamford Laundry premises close to the address, and is thought to be one of many letters sent to local residents informing them of a possible change of use to the site.

Harrison Murray estate agency manager Zara Laxman said: “We were all very excited and intrigued when the letter arrived in the office only last week – having looked at the postmark and seeing how long ago it was originally sent.

“A member of staff opened the letter and the mystery now centres around its whereabouts for the past 40 years, and what the people at Roman Bank in Stamford thought of the plans at the time.”

In 1975, Mrs Thatcher beat Edward Heath in the Conservative party leadership election, a tube train crash at Moorgate Station in London killed 43 people, and Brian Clough was appointed manager of Nottingham Forest.

Zachary Oldershaw, 20, negotiator at Harrison Murray inspects the letter which was posted two decades before he was born