The National Trust may be forced to amend its plans for a historic neo-Gothic mansion near Bristol, after it emerged the building was home to colony of rare bats.

Tyntesfield, a spectacular Victorian mansion at Wraxhall in North Somerset, is crammed full of relics from the British empire.

But trust officials have admitted it may also house an important colony of one of the rarest bat species in Britain.

Bat experts at the trust say the Victorian house provides a habitat for Greater Horseshoe bats.

Rare bats

Many of the buildings are known to be good roosts for the bats, according to Phil Richardson, the trust's bat conservation officer.

As the house and its many surrounding buildings are in an area known for Greater Horseshoe bats, he believed it could prove to be an important habitat.

However, as specially-licensed bat handlers will be unable to survey the estate until contracts are exchanged, the true extent of its importance as a colony for rare bats will not be known.

William Gibbs - a merchant who made part of his fortune by importing bat droppings from South America as fertiliser - built the house in 1875.

At that time, there were thought to be about 300,000 Greater Horseshoe bats in Britain.

The house retains many original features

But loss of the creature's natural habitat and increased use of insecticides have reduced their numbers to about 4,000.

Mr Richardson said: "Tyntesfield is slap bang in the middle of an area rich in Greater Horseshoe bats.

"Properties around have good numbers of this species and plenty of records of them foraging throughout the landscape.

"As well as this, the house is on a south-facing slope which is ideal for bat roosts as they are warmer and tend to attract plenty of insect food.

"And the fact it has not been altered over the years means any bats living there would not have been disturbed."

The National Trust, which takes over control of the house later this summer, was able to acquire Tyntesfield after being awarded a �17.4m grant from the National Heritage Memorial Fund.

The grade one listed home is renowned for its sumptuous private chapel, an unrivalled collection of Victorian art and 500 acres of beautiful landscaped garden, park and farm land.

The estate and house came on to the open market with the death of Lord Wraxhall in 2001.