A set of rare photographs showing the first tanks being tested in Lincoln has smashed its guide price at auction.

The album, which contains around 50 black and white press pictures of the First World War tank, fetched £4,600.

It was originally estimated to sell for between £200 and £400.

The collection illustrates the development of the machine at Lincoln engineering firm William Foster and Co, which was based in Waterloo Street and famously created the Mark I tank, nicknamed "Mother", in 141 days during 1916.

The tank then went on to change the face of the war.

Photographs of unusual prototypes and failed attempts to cross trenches are among the most revealing inclusions in the album.

Experts say the images are so rare because there were limited opportunities to snap the top-secret weapon during its creation.

And many documents and images perished or were destroyed in the years following the war.

The winning bidder was said to be a private local collector of Lincolnshire-related memorabilia.

He beat competition from five other bidders in an auction last week.

John Leatt, from Lincoln auctioneers Golding Young and Thomas Mawer, said there were several reasons why the album might have sold for so much.

He said: "It was a big surprise.

"But I think the condition of the album was very good, considering they were things that were generally thrown away and could be easily damaged.

"And they are very rare.

"We know of a number that have come out, but not many over the last 20 or 30 years."

The album was the property of an unidentified Lincoln woman whose family received it from a worker at William Foster and Co.

Historian and Friends of Lincoln Tank chairman Richard Pullen explained there were few records of the tank in its prototype stage.

He said: "Recently there has been a huge escalation in the interest for these sorts of items.

"Sometimes single photographs can go for £50, £60 or £70, so for a whole album of them, the sky is the limit.

"I know of several old photos of the testing and building process, but every so often there are some that emerge that haven't been seen before, and they can be very sort after.

"It was top secret, so to have a photo of them is very rare.

"Some press photographs were shown at the time, but some of them might not have been seen for more than 100 years.

"It's great they have survived for future generations to see."

The lot also included catalogues of traction engines, motor wagons and other vehicles from Lincoln engineering companies.

A photograph of the Hornet tank being presented to Queen Mary and King George V by Sir William Tritton in 1918 was also on sale.