A remarkable archive of letters from the late and brilliant Alan Turing in the mid-20th century has been found hiding in a storeroom at the University of Manchester in the UK.

The find of 148 documents was made by Professor Jim Miles of the School of Computer Science, who had been reorganizing the storeroom when he came across them. The letters date from early 1949 until Turing’s tragic suicide in June 1954.

“When I first found it I initially thought, ‘that can’t be what I think it is’, but a quick inspection showed it was, a file of old letters and correspondence, by Alan Turing,” said Professor Miles in a statement. “I was astonished such a thing had remained hidden out of sight for so long. No one who now works in the School or at the University knew they even existed. It really was an exciting find and it is [a] mystery as to why they had been filed away.”

Although the letters reveal little about Turing’s personal life, they do show how highly regarded he was at the time. This is despite his work at Bletchley Park, when he helped crack the German Enigma machine in World War Two, still being under wraps.

He had numerous offers to lecture at universities or attend events in the US, based on his previous work on artificial intelligence, computing, and mathematics. One of these was from the Massachusetts Institute of Technology (MIT).

However, it seems Turing himself wasn’t that keen on going to the US. In response to one invitation in April 1953, he said: “I would not like the journey, and I detest America.”

Another batch of letters found in 2015 shed more light on Turing’s tortured personal life, which saw him prosecuted for homosexual acts in 1952. He was later pardoned posthumously in 2013, having committed suicide via cyanide poisoning in 1954.

While these latest letters do not reveal any more about his personal life, they do give us more of an insight into his professional life. You can view all of the letters online here.

“The letters mostly confirm what is already known about Turing’s work at Manchester, but they do add an extra dimension to our understanding of the man himself and his research,” said Archivist James Peters in the statement. “As there is so little actual archive on this period of his life, this is a very important find in that context. There really is nothing else like it.”