A powerful main line diesel locomotive has been officially named 'Royal Corps of Signals' to mark a valued 33 year association with the Swanage Railway.

The naming of the 129-tonne Class 66 locomotive No. 66 756, belonging to main line freight train operator GB Railfreight, at Swanage station came on national Armed Forces Day, Saturday, 24 June.

Performing the honours in front of guests, members of the military and the public were Major General John Crackett, of the Royal Corps of Signals, whose headquarters are at Blandford Forum in Dorset, and GB Railfreight managing director, John Smith.

Since 1984, a total of 5,000 servicemen and women from the Royal Corps of Signals have taken part in 65 exercises on the Swanage Railway, as the heritage line has developed, with the troops also helping the wider community in Swanage.

Swanage Railway volunteer Frank Roberts, a serving member of the Royal Corps of Signals for 25 years said: "It was a great day. The locomotive naming was a very proud moment for everyone in the Royal Corps of Signals, both past and present.

"It's wonderful to think that the Royal Corps of Signals will be seen countrywide as the locomotive hauls freight trains across the national railway network. I'm very grateful to John Smith for kindly allowing one of the company's locomotives to be named after the Royal Corps of Signals.

"I would also like to thank the Swanage Railway for allowing the naming to take place at Swanage station and for staging a special train – hauled by No. 66 756 – carrying dignitaries and guests. It was a memorable day and one that I won't forget for a very long time."

The naming of the GB Railfreight diesel locomotive was the first time that present and past members of the Royal Corps of Signals had enjoyed a reunion in Swanage since 2005, when the Corps was given the freedom of the town of Swanage.

As the Swanage Railway has steadily extended its train operations – to the three mile point at Harman's Cross in 1988 and the five mile point to Corfe Castle and Norden in 1995 – so have members of the Royal Corps of Signals carried out exercises to install lineside telephone poles, phone lines and also telephone exchanges.

Mark Woolley, a trustee with the Swanage Railway Trust and a director of the Swanage Railway Company, said: "Everyone on the Swanage Railway would like to thank the Royal Corps of Signals for its generous help and support over the past 33 years which is very much appreciated.

"In addition to strengthening the relationship between the Swanage Railway and the Royal Signals, we were happy to support the naming of the Class 66 locomotive as it promoted our engagement with, and support for, the wider railway industry."