A MAN who carried out ‘top secret’ work during the Second World War has revealed how he helped develop codebreaking machines at Bletchley Park – but only realised his part in defeating Hitler 50 years later.

Roy Howard, of Pocklington, who celebrated reaching his 100th birthday last month, worked as an electrical engineer throughout the war.

Years afterwards he said he developed a keen interest in the work of legendary codebreakers such as Alan Turing and their work at Bletchley Park cracking the German Enigma and Lorenz codes.

The work was instrumental in helping British troops to defeat the enemy as it allowed them to stay one step ahead of German plans for attacks on the allies.

One day, while reading a book about the codebreakers' exploits, Roy recognised a circuit he had worked on.

He said: “I had always been personally interested in the work that went on at Bletchley Park, it always fascinated me.

“When information about the work there began to be published, I was very surprised to recognise an electrical circuit that I recalled being asked to work on under great secrecy.

“I now realise that it was to be for the decoding of German military teleprinter signals, using the analysis provided by what has become known as Colossus.”

Roy also worked with Tommy Flowers - who designed and built the Colossus machine.

“I worked very closely with Tommy, but he never told us about the work he was doing as he was sworn to secrecy,” Roy said.

Back in the late 1930s Roy was a very young engineer who had only just finished his basic training when he was asked to work in a laboratory near St Paul’s Cathedral in London - where he was then based for all six years of the war.

Roy was employed to test electrical equipment by carrying out point-to-point checks to examine whether it was all working correctly.

Roy said: “I was required to sign the Official Secrets Act in 1939, which bound me to work with things marked as ‘secret’ and never talk or write about such things unless specifically commanded to so do.

"Signing the document bound all who dealt with this kind of work to great secrecy about such things as locations of special equipment which we had to know about to fit it and maintain it."

The Colossus was not the only machine that Roy worked on that was instrumental in winning the war.

He recalls working for several weeks at RAF Kidbrooke, building the communications parts of Ground Control Interception (GCI) units - highly secret radar equipment used for detecting low-flying aircraft.

In the 1960s Roy was surprised to discover that his wife, Muriel, had also worked with the GCI units, as she worked with the Air Ministry and had been responsible for arranging the shipment of the equipment.

“It was such an unbelievable coincidence,” he said.

After the war, Roy continued to work in electrical engineering in both the UK and the Netherlands - where he worked for SHAPE (Supreme Headquarters of Allied Powers in Europe) on more classified initiatives.