IT was a red letter day for police when an envelope dating back more than 150 years came through the door.
Officers were shocked when a local man handed in a package at Alsager containing a piece of history which goes back to 1843.
The envelope, which did not contain a letter, is most notable for containing two Penny Red stamps, a prized possession among collectors.
The Penny Red stamp was issued in 1841 replacing the Penny Black.
The tiny envelope, which was bound for Edinburgh, is marked April 23, 1843 and has a wax seal.
The package was handed in by an unidentified thought to be in his 60s.
He had found the envelope on a photocopier at Martin newsagents in Crewe Road on Wednesday morning. Realising its value he handed it in to police the same day.
Police did not realise what they had on their hands until Monday. They are now searching for its owner.
PC Carl Hurstsaid: 'I have neverseen anything like this before. It's really quite remarkable.
'It was a bit of a surprise when I opened it up.
'The only thing more surprising I can think of that has been handed in is when a baby was handed into Alsager police about 15 years ago.
'We want to find the owner of this envelope as we are sure it is of value to them.'
Police say they will be able to identify the owner as he or she will know the address on the envelope.
The anonymous man who handed in the envelope has asked for any reward to be given to charity.
Gilbert Band, from the Alsager History Society, said: 'It's an interesting find. I am sure there is a really interesting story behind the letter.
'We need to know who has written it and where it turned up. We don't know anything about it an the minute.
'They are not Penny Black stamps which is a shame because they are worth a lot of money but they are still of interest to collectors.'