A rare picture of the Watford FC first team squad in 1920 has been discovered in Suffolk.
The postcard-size image is thought to have been produced by the club and sold at the stadium to fans.
It is being sold as a premium item at an auction in Suffolk later this month because auction house experts have never seen anything like it before.
The picture was found among a collection of cigarette cards, but the size of the item is highly unusual as cigarette cards were traditionally the size of a packet of chewing gum.
Lockdales, the auctioneers of Martlesham near Ipswich, will put it under the hammer on September 14 at a catalogue guide price is £100 to £150.
Chris Elmy, cataloguer for the auction house, said: "It came out of a very large collection of cigarette cards. Normally these collectables are quite small, but this image is bigger than a postcard.
"It was issued in the 1920s, possibly produced by the club and sold at the stadium.
"This particular image is very, very rare. We have it listed as premium issue.
"We have estimated the lot will go for between £100 and £150, but football memorabilia is difficult to price because there are some fanatical collectors about."
The picture shows the team from 1920 to 1921 in their striped strip, surrounded by coaches and managers in traditional dress of the era.
In the catalogue the lot is described as Football Teams (Premium issue) type card, Watford A.F.C. 1920-1921. It is further noted as "a previously unknown subject" which means neither the auction house expert or any other expert has seen this sort of item before.
It was stated to have a horizontal crease and to be a "very rare item".
Auction manager James Sadler added: "There has already been a great deal of interest in this wonderful old football picture."