The Big Question: Should badgers be culled to prevent the spread of tuberculosis in cattle?

What, Old Mr Brock, one of our best-loved wild animals? Why do we need to?

Because bovine tuberculosis is now one of Britain's principal animal welfare problems, with livestock farmers saying it is starting to threaten their livelihoods, and there is strong evidence that in some areas, wild badgers carry it, and are responsible for its spread in cattle herds.

Is this a new discovery?

Not at all. But the question arises now because the arguments over it will shortly come to a head, when an independent committee of scientists reports to the Government on whether or not a widespread TB-related badger cull would be justified, and/or effective, after nearly a decade of studying the problem.

That seems like a pretty long time to study it, doesn't it?

It's turned out to be a difficult problem, to be honest. There are passionate feelings on both sides of the argument. Britain's cattle farmers feel very strongly that badgers are spreading TB amongtheir herds, and feel that a widespread cull in areas of infection is essential. Britain's badger-lovers - and there are a surprising number of them - formerly organised as the National Federation of Badger Groups, which has now become the Badger Trust - forcefully assert that a cull would be extremely cruel, unjustified, and ineffective. The position of each side is strongly held but essentially a simple one.

So what do the scientists say?

Ah well, they say that the picture is much more complex. Brought together in the Independent Scientific Group on Cattle TB or ISG, they have been looking at the question since a 1997 report from a senior zoologist, Sir John Krebs (now Lord Krebs) of Oxford University, one of Britain's leading animal behaviour experts.

Krebs felt that the link between badgers and TB in cattle was clearly established. He said: "The sum of evidence strongly supports the view that, in Britain, badgers are a significant source of infection in cattle. Most of this evidence is indirect, consisting of correlations, rather than demonstrations, of cause and effect; but, in total, the available evidence, including the effects of completely removing badgers from certain areas, is compelling."

But what was missing, he said, was any proper scientific evaluation of how different strategies for killing badgers - partial removal, total removal - might reduce bovine TB infection in any given area, and whether they would be cost-effective (for they would certainly be expensive). To this end, he recommended the setting up of a large-scale experimental culling trial to find out.

And this experiment has taken 10 years?

Not far short. And it's cost £34m, and the lives of about 12,000 badgers, most of which have been cage-trapped and then shot. It's taken so long because the Randomised Badger Culling Trial (RBCT) has been a very large-scale undertaking: culls have taken place in 10 trial areas. Two types of cull took place: so-called proactive culling, which aimed to reduce badger numbers to low levels over areas as large as 100 sq km, and reactive culling, which was to kill badgers only near TB-infected farms. But then there was a serious, and quite remarkable, problem.

What was that?

In the late autumn of 2003, the scientists realised that their experimental culling was helping to spread TB further in badger populations.

Really? How on earth could that happen?

It seems to go against common sense, doesn't it? But the scientists supervising the trials explained that, in practice, no more than 80 per cent of badgers in the infected area were being caught. The survivors were no longer living in stable social groups, and were more likely to wander about the countryside, spreading disease as they went. Reactive culling was found to be causing a 27 per cent increase in TB outbreaks. Professor John Bourne, chairman of the ISG, said at the time: "I think it shows very clearly that badgers are involved in the transmission of TB. What it goes on to show is that localised culling will not control TB in cows, but will be likely to make it worse." How d'you get out of that one?

So when will we get the scientists' final recommendations?

They are due to report in mid-June. But whether they say cull or no cull, the ministers are not bound to accept the recommendations, although the British government has always liked to "follow science" in such situations.

Would a widespread cull be a difficult political decision?

You betcha. Last year, the Government attempted to test the temperature of the water by holding a consultation exercise on the possibility of a cull. There were more than 47,000 responses, and 95.6 per cent of them were opposed to killing. The Badger Trust is by no means alone in opposing any cull: the RSPCA, the Mammal Society, the National Trust, the Wildlife Trusts and the Woodland Trust are all very much against. It would be immensely unpopular with much of the public.

But not with farmers?

No. Livestock farmers are increasingly frustrated and angry with what they see as an obvious cause and effect with badgers and the increase in bovine TB, and nothing being done about it. Incidence of the disease has gone from a few hundred animals a year 20 years ago to nearly 20,000 last year, with about 7,000 of Britain's 90,000 livestock farms affected by movement restrictions at any one time. Farmers say the reason for the TB increase is simple: an enormous increase in the population of British badgers over the past 20 years, because of the warmer winters brought about by climate change, and because badgers have gained legal protection in Britain with a series of measures culminating in the Badger Act 1992, which made it an offence to disturb a badger's sett.

Have badger numbers shot up?

There is anecdotal evidence that they have. Scientifically, the position is less certain. Two national surveys of badger populations were carried out by the University of Bristol, in 1990 and 1997. The first gave a population estimate of 250,000 adult badgers. The second, although it did not give an overall figure, estimated that badger numbers had increased by 97 per cent since the first survey, and that sett numbers had gone up by 24 per cent. It is certainly the case that with fewer freezing nights to make digging for earthworms difficult, and with complete legal protection, life for Mr Brock in Britain is probably as good as it's ever been.

Does the problem of bovine TB justify a mass badger cull?

Yes...

* There is clear evidence that in some areas, badgers form a reservoir of infection for bovine tuberculosis

* There is evidence that the spread of bovine TB through Britain's cattle herds has been caused to some extent by badgers

* The problem is becoming so serious for Britain's livestock farmers that it cannot simply be ignored

No...

* There is no certainty that a culling programme would work; indeed it might have the opposite effect of spreading TB further

* Other measures, such as improved biosecurity on farms, might be more effective

* Culling would amount to the cruel and unjustifiable mass slaughter of one of Britain's best loved wild animals