ENTHUSIASTS are set to come together to mark a remarkable feat of Victorian engineering, as the Severn Tunnel celebrates its 125th anniversary.

When the tunnel opened in September 1886, it marked a new chapter in Monmouthshire's history allowing the first regular rail traffic between England and South Wales.

Next weekend members of Sudbrook Community Council, Caldicot and District Local History Society, Sudbrook Non-political Club and Sudbrook Action Group, are holding 125th anniversary celebrations when John Harvey, great-grandson of engineer Thomas Walker, will officially open Sudbrook History Centre.

The Great Western Railway (GWR) Company started constructing the tunnel as a way of transporting coal from South Wales to England in 1873, sinking a shaft near the deserted medieval settlement of Sudbrook.

Six years in, the project was nearing completion when disaster struck. Tunnellers on the Welsh side hit an underground spring flooding the tunnel with hundreds of gallons of water.

Fortunately no one was hurt, as the workers were changing shift, but all work stopped as attempts to pump the tunnel dry proved fruitless, as the spring was discharging 15 million gallons of water a day.

It was only when GWR contracted the project to Thomas Walker, that work got back on track. Mr Walker created homes for the huge workforce needed to complete the tunnel, he built the village of Sudbrook, with a school, hospital, mission hall and coffee house.

The four-and-a-half-mile tunnel was completed in 1887 and for more than 100 years was the longest mainline railway tunnel in the UK.

During the Second World War, the tunnel provided a haven for a GWR passenger train being pursued by a German aircraft along the main line to Wales and in 1991, 185 passengers were injured, five seriously, when a Class 155 Super Sprinter from Portsmouth crashed into the back of another train.

Mr Harvey said he started to find out more about the achievements of his great-grandfather when he was in his late 50s.

He said: "As a family, we are extremely proud of him. One of the great sources of reference was a scrapbook kept after his death by my grandmother. It contains 250 press cuttings from when he built the tunnel.

"What became very interesting was he was obviously very well regarded, an innovator in many ways. He was consulted by the French on the building of the Panama Canal and proved it was totally feasible to have a Channel Tunnel."

Mr Harvey will officially open the history centre at 11am on September 5, and give a talk about Mr Walker's achievements. There will also be stalls, a model railway display and performances by the Severn Tunnel Band.

Pete Strong, Caldicot and Distrcit Local History Society, said: "The whole community was built by Walker to house his workers, hardly anything pre-dates that period and it still has it's Victorian character.

"This will be a celebration of the tunnel and the community that came into existence around it so everybody is invited."