The roosts of bats are protected by conservation laws

Clifton Hall in Nottingham is Grade I listed but the bats live in a 1960s extension which is not protected.

The small mammals are protected by law, so developers cannot do anything that would disturb their roost.

The developers, who want to convert the hall into expensive apartments, have modified a building close to Clifton Hall to try and entice the bats to live there.

Each summer 200 pregnant bats return to Clifton Hall but it is hoped this year they will switch to the neighbouring building.

Architect, Ben Crouser, says it has cost �25,000 trying to coax the bats out.

"We specialise in the restoration of listed buildings and virtually every single site we work on we are dealing with bats.

"We are having to relocate them or even better we encourage them to stay in the buildings we are redeveloping."