Oxford University researchers are launching a new app that asks people to help identify old pictures ranging from flooded city streets to pre-First World War spy photos.

The Historic Environment Image Resource (HEIR) is an archive of 38,000 digitised slides which until now has remained uncatalogued.

Researchers at the Institute of Archaeology have already digitised 11,000 of the 100-year-old images, all taken by Oxford academics, and will soon be releasing an app to allow people view the images and help identify them.

Project co-director Dr Sally Crawford said the images would become available from May.

She added: “There will be a searchable database, and a mobile app which will allow people to re-photograph the modern place, side-by-side with the old image.

“Anything we have got in our archive will be available to look at.

“We have local pictures of the trams and colleges of Oxford, of streets flooded, and excavations in the city, and we are going to use the power of crowd-sourcing to help us identify them.”

Slides from around the world will be available to view, including a few surprise discoveries which have already been made.

Dr Crawford said: “Our volunteers were digitising images by John Myres of Greece and Crete from the 1880s-1900s, and they commented that for an archaeologist, there are a surprising number of pictures of warships and harbours.”

Born in 1869, Mr Myres was an Oxford don and archaeologist who travelled extensively throughout the Mediterranean in the late 1800s and early 1900s.

When the First World War broke out, however, he became a captain in British Naval Intelligence and was nicknamed the Blackbeard of the Aegean for his unerring attacks on strategic military sites in the area.

Dr Crawford said: “These discoveries were a bit of a surprise. Was he gathering military intelligence before the war?

“British archaeologists have long insisted that while other countries used their schools in Athens for intelligence gathering, the British never did anything like that.

“But there are pictures titled Piraeus – Russian Man O’War, and Crete – Inside the Insurgents’ Headquarters.

“These are not archaeological photos. If Myres happened to be taking pictures and there just happened to be a Russian warship in the way, so be it.

“And if some nice Cretan insurgents invited him back to theirs for a cup of tea... Well, he wasn’t going to say no.”

The app and database will be released on Friday, May 15, to coincide with the Ashmolean Museum’s LiveFriday event.

Dr Crawford added: “What other stories might be uncovered in the archive?

“There are many images where different eyes will be able to see something we don’t. That’s why this resource is too important to lose.

“These are pictures that in many cases have not been looked at for a hundred years or more, and they are stuck in an archive when they should be available for everyone to see.

“I was trying it out in Cornmarket the other day.

“I took a picture of St Michael at the Northgate and I was able to see it alongside the old picture.

“It was really interesting to see how the old building next to it has changed over the years.

“We’re hoping people can use the app as a sort of a treasure hunt. There are images from all over the world including a large collection of mystery photographs that we’re hoping people can help us identify.”

For more information on HEIR’s work, head to arch.ox.ac.uk/HEIR.html