A hairline crack in a crumbling section of Sidmouth’s cliffs has grown to several inches over the last year – but County Hall chiefs say intervention risks accelerating the erosion.

Dog walker Billie Ivey raised concerns about the sandstone face near the Ham’s water treatment plant after seeing the ‘shocking’ increase of the void over a short period.

She said the town’s focus is on Pennington Point - but falling rocks could overwhelm the River Sid. Last year, it wasn’t much more than a hairline crack,” said shop keeper Billie, who runs Artisans.

“I didn’t see it for a while and suddenly it was much wider – it was quite shocking.

“Some of the trees are dying. Once the roots break there will be nothing holding it up.

“No-one’s talking about that part of the cliffs, and there may be good reason for that, but if it fell it could cause flooding.”

She said that section of the cliffs needs to be included in the beach management plan that East Devon District Council is drafting. Flooding is the remit of Devon County Council, where the member responsible is Sidmouth’s own Councillor Stuart Hughes.

He said: “Vertical fissures like this are common in sandstone cliffs and, yes, the boulder may eventually fall away - but there are numerous such sites along Devon’s cliffs and it would not be feasible, or even desirable, to tackle each site.

“We could scale down the face and force the piece to fall in a managed way for removal, [but] the problem with this is you expose new rock behind and that would encourage further erosion, not something we would want to do.

“The risk of the rock falling into the river and causing flooding is small.

“So we are going to leave it as it is and will ask the East Devon bridge inspector, who checks Alma Bridge on a regular basis, to monitor the cliff face at the same time.”