We have a lovely 1350s church, with lime-wash walls, but bats have turned two corners of the nave walls a horrible grey. Is there any way we can clean up the mess rather than have to pay for the whole nave to be re-limewashed? And is there a legal method of keeping them out of the nave? They seem to fly there only at night, and roost outside.

BECAUSE I have little knowledge about bats — apart from the time a sick bat dropped down my vicarage chimney, and the RSPCA wanted me to return it to the top of the chimney — I searched the churchcare.co.uk website.

I now know a lot more about bats, but, I regret, not enough to solve your problem.

The bat droppings indicate their access point, and probably also their roosting place, between the top of the walls and the rafters. If they are not actually roosting in the church, you could probably just close off the access point, although they might simply find another.

I am sure that a rural diocese such as yours must have previous experience, and the secretary of the diocesan advisory committee (DAC) may be able to refer you to a suitable specialist to advise on what is possible in deterring the bats and avoiding the damage.

Bat urine is 70 per cent urea, a kind of ammonia that is strongly alkaline. It is quite likely that even if a fresh coat of paint is applied to the affected area, the damage underneath will quickly show through.

Limewash allows walls to “breathe” and dry out; using a less permeable paint to cover the bat urine would damage the church’s walls, as dampness would build up. So even a coat of paint will need expert advice from a conservation architect, or someone similar. This will all be particularly difficult if the bat expert and legal advisers say the bats have to stay.

The first step is to get details of specialist advisers from your DAC secretary. Natural England is the organisation that would issue a licence giving permission for any work that affects bats and their habitats, and you may be required to justify the interruption to the bats. It is likely that only your conservation architect will be able to prepare this for you.

This is a legal issue, because bats are an endangered and declining species that is protected by the 1981 Wildlife and Countryside Act. Some people love them. I don’t, but I do not begrudge them their survival. Let me know if and when you find a solution — for you and for the bats.

maggie.durran@churchtimes.co.uk