A Wiltshire couple who let out their four bedroom property suffered a nasty shock when carrying out a routine inspection of the house, according to the Daily Mail, as they found that the tenants had turned it into a cannabis factory.

And with the Association of Residential Letting Agents (ARLA) revealing that this is a problem that has been encountered in the private rental sector by police forces around the country, it appears that landlords need to be extra vigilant when it comes to the activities of their tenants.

"There were hundreds of plants, masses of lights and cables everywhere and ducts going up through the roof," said Shaun Thomas, who owns the house in Wiltshire with his wife, Katie.

"There was an electrical board with 15 boxes to power the lights."

With Dorset witnessing a 550 per cent rise in the number of cannabis farms discovered in the past two years, ARLA has published a list of recommendations to help landlords ensure that their tenants are not breaking the law in their properties.

Asking neighbours to watch out for any suspicious behaviour was included among the guidelines, as was checking for extensive fuel bills and looking to see if the windows of the building were permanently covered from the inside.

Indeed, while landlords are required to maintain their properties to a good standard, it's not possible to carry out especially frequent checks on all of their assets, so asking neighbours to keep an eye on things could be particularly useful.

What's more, with Mr and Mrs Thomas facing an extensive bill to repair their property as they had not purchased a landlord insurance policy comprehensive enough to guard against malicious damage, it could be that investors check that their own policies are more extensive than that which the Wiltshire couple had in place.