Cyclists who repeatedly damaged an historic north Wales mansion have been told “enough is enough”, writes Gareth Hughes.

For the past six years mountain bikers have stayed at the residential Plas Tan-y-Bwlch, near Maentwrog, during the Red Bull Hardline event, which is billed as “the toughest and gnarliest” downhill race in the world.

But the Snowdonia National Park Authority, which owns the environmental study centre, has told them they must find somewhere else to stay this year. Members of the authority said that damage caused to the property on the last two visits meant that the risk of further damage was too great.

Details of the damage have not been disclosed but a hint was given by an authority spokesman who said: “Main costs included refills of fire extinguishers and other additional cleaning and cosmetic damage.”

The mansion, a Grade II listed building, can accommodate 60 people and the spokesman said: “Red Bull booked the whole property for the Hardline weekends and have been responsible for all guest bookings and numbers.”

Last year Red Bull forfeited its £5,000 deposit and has paid for all the repairs.

At a recent meeting of the management committee one member asked whether Plas staff were present during the weekend and according to the minutes was told by director of corporate services, Iwan Jones, that “staff were present during the day but weren’t comfortable to stay overnight”.

Plas Tan-y-Bwlch was built by the Oakley family, owners of nearby slate quarries, in the 19th century, on the site of earlier mansions dating from the 16th century. It stands in six acres of gardens which are also Grade II listed.

Overlooking the River Dwyryd, it was the first house in North Wales to have electric lights powered by its own hydro-electric scheme, which was commissioned in the 1890s.

The decision to withdraw from the agreement with Red Bull is a financial blow to the authority and Mr Jones told the management committee it would be difficult to find an income source to match it.

But the minutes state: “Members were concerned that should they return to Plas the damage caused could be much more significant and it was too much of a risk”.

This year’s Hardline event is being on July 15-16 in the Dyfi Valley near Machynlleth.

Red Bull has been asked to comment.