Bat mitigation measures now include special bridges so they can cross roads safely. Is it time for an independent review of what all this is costing us and what good any of it really does?

Charlotte and Brian Paton gave up in the end, like many others who have crossed swords with Natural England over bats.

Instead of the loft conversion they wanted, they ended up with a compromise in the shape of a more expensive extension and a little less garden, after a three-year battle with officialdom.

Now the Patons believe it's time for an independent review of so-called mitigation measures and whether they are always necessary.

Millions are being spent on the latest conservation wheeze – bat bridges, which enable the creatures to safely negotiate new roads like the last dualled section of the A11.

Manchester Airport has had to build three large barns to accommodate thousands of Pipistrelle, Brown Long-eared and Brandt's bats made homeless when it knocked down buildings to make way for a new runway.

Bats even blocked the Dale Farm eviction, when their droppings were found in a caravan on the site.

Ounce by ounce, pound for pound, bats probably have more money spent on them than species which are clinging on for survival, like the bittern, red squirrel or even the Atlantic salmon.

Some years ago, author Mrs Paton and her husband – a retired surveyor – asked for advice from one of Natural England's predecessors, before treating timbers in their roof.

A dozen or so brown long-eared bats (Plecotus auritus to their friends) lived for part of the year in the roof space of the couple's Hansel and Gretel-esque home, a carrstone gate lodge tucked away on the edge of a wood near King's Lynn.

Got bats? No problem, was the response. Sounds like it's probably a maternity roost. Just do the work in the winter, when they're off hibernating somewhere else.

So that's what the Patons did. The bats flew on cue. Timbers treated. Job sorted. No harm done.

Mrs Paton rang Natural England, after the council gave them planning permission for the loft conversion in 2007, expecting it would be equally simple.

'They said you can't do that,' she said. 'You can't do that at all. They just said no. End of. We had to have this bat survey done. They said you have to have the people we recommend at the price we say.'

The couple were soon immersed in correspondence on suitable mitigation measures. Natural England sent a licensing officer out to see them.

The Patons were told they could possibly leave two thirds of the roof for the bats, and convert the remaining third for themselves.

Then again, they might have to construct a roof alongside the house instead, matching the existing space as closely as possible, creating a home from home for the bats.

Or they could look to provide an extra loft by lowering the ceiling elsewhere in the house.

But either way, the experts would have to be called in to do a bat survey, just to make sure. That would take three nights – at �1,000 a time. They couldn't shop around either, as Natural England will only consider reports from its list of approved ecologists.

'They were talking about building another roof in the garden. It was just getting more and more ludicrous,' said Mrs Paton. 'They wouldn't say what they would and wouldn't allow us to do until we'd had this survey.'

If you don't like it, of course, you can always appeal – to Natural England.

'Natural England is the police force, the judge, the jury and the appeal court,' said Mrs Paton.

'They've got a complete monopoly over it. You're not allowed to have a different view.

'Everywhere else in the English justice system there are checks and balances, there's always a right of appeal, but this is a complete closed shop.'

Some in the countryside speak of more drastic solutions, ranging from a loud radio left on in the attic to a hose from a car exhaust fed under the eaves.

Disturbing bat roosts is illegal – let alone killing them. Both almost certainly go on in Norfolk and elsewhere. Mr and Mrs Paton received anonymous phone calls offering 'advice'.

Like many who live in the countryside, the Patons are passionately pro wildlife. They just wonder whether the line is sometimes being drawn too far in nature's favour.

Had they built their loft conversion, would the bats not simply have flown the coop and found another roost, in any case. And would anyone have been any the wiser had they not volunteered the fact that they had bats in the first place.

Instead the whole saga took three years and cost the Patons thousands, before they threw the towel in and built an extension instead of a loft conversion.

'It's costing the country a fortune,' said Mrs Paton. 'We need an independent body, a university or something to do some research, some independent research into it.

'All the research so far has been done by the bat people, who have an agenda. It's preserve bats at all costs. I'm not saying let's destroy them, but it must be costing the country millions.'

Natural England receives around 700 applications a year for bat mitigation licences. Matt Heydon, one of its regulation officers, said: 'Bat populations have undergone significant decline in recent years, and receive special protection as a result of this vulnerability.

'Loss of traditional woodland habitat and intensive agriculture has seen many bat species becoming dependent on buildings for roosts.

'We do appreciate that this can cause difficulties for some homeowners, but with proper planning it is usually possible to accommodate most development.

'Essentially we need to ensure that there is no 'net loss' to roosts as a result of disturbance or destruction and no-one is asked to do more than is necessary to achieve this.'