After an absence of approximately 400 years, wild boar are roaming and breeding in the Scottish countryside once again. They were reintroduced to the Highlands in 2009, and seen as a way of destroying bracken and helping the growth of native trees, including Scots pine, rowan, aspen and juniper, as well as woodland flowers.

The wild boar, spotted mostly in Lochaber and Dumfries and Galloway, have either escaped or been freed from farms where they were being reared for meat.

However, they have become such a problem for farmers that there have been calls for the Scottish Government to take action before the numbers of animals on the loose become unmanageable. Farmers whose crops are destroyed by wild pigs have threatened to demand compensation worth tens of thousands of pounds if the government fails to cull them.

Failure to act could lead to the kind of problems being experienced in the Forest of Dean, where the latest cull of wild boar in the Gloucestershire and Herefordshire forest has clearly failed.

The most recent survey figures, from March 2016, estimated there were 1,562 feral wild boar roaming the forest, 50 per cent up on the 2015 estimate. Populations of wild boar are also spreading to new areas.

The surge in numbers occurred despite a cull of more than 400 wild boar in the forest and experts are warning the population could hit 10,000 within a few years unless proper controls are put in place. While it is not illegal to shoot wild boar, the animals are elusive, nocturnal creatures, meaning humane killing is a skilled and time-consuming task.

National Pig Association (NPA) chief executive Dr Zoe Davies said: "Feral wild boar pose a very genuine threat to the British pig industry.

"These pigs are gaining access to waste food when they root around in household bins and at picnic sites. We need to be mindful that in Eastern Europe wild boar have been integral in the spread of the deadly African swine fever (ASF) virus."

By mid-August there had been more than 160 ASF outbreaks in Russia alone, with vets expecting 2016 to be the worst year on record.

ASF is a highly contagious hemorrhagic disease of pig and wild boar affecting all age groups. With high virulence forms of the virus, ASF is characterised by high fever, loss of appetite, haemorrhages in the skin and internal organs, and mortality rates up to 100 per cent.

Transmission can be through direct contact between sick and healthy animals, and through feeding infected meat and via vehicles, implements and clothes, as well as biologic vectors such as soft ticks.

Dr Davies stressed that: "If an exotic disease like ASF got into the UK's wild boar population, it would become almost impossible to prove that the disease had been stamped out. This would wreck our burgeoning export market, now worth £350m a year, with devastating consequences for the industry.

"In addition, local businesses and tourism would suffer greatly as the whole area would be under restriction indefinitely. We only need to look back to the last foot-and-mouth disease outbreak to know exactly what impact this can have on local communities."

Wild boar in the Forest of Dean area have increasingly been causing havoc among the general public, with reports of animals wandering around town centres, wrecking bins and gardens and chasing dog walkers. There have been 49 wild boar related road traffic accidents in the area recorded since April.

I have good friends farming in Normandy where there are wild boar roaming in the woodland surrounding their dairy farm. I have seen firsthand the damage they can do to crops, grassland and fences.

The couple grow maize for silage, and wild boar find the cobs irresistible. Not only do they eat the cobs, flatten and trample the crop, but their rooting activity makes an awful mess of the field. It's much the same with newly-sown fields and young grass leys where they root about in the recently-worked soil.

If the Scottish Government decides to allow wild boar to continue to carry on living in the wild in Scotland, then it will have to compensate farmers for the inevitable damage they will cause. Compensation rates of €10,000 per hectare can be achieved in other European countries, as that's what it costs to re-establish a field of grass and suffer the loss for a year or two of a crop of hay.