Up to £150,000 worth of cannabis plants have been found in a drugs raid on a flat above an empty shop in the Black Country.

Police raided the factory at 123 High Street, Brierley Hill, above the vacant Nail Bar shopfront after months of gathering intelligence. They found 542 plants in various stages of growth and arrested a man found hiding on the roof. Eight officers, including two Police Community Support Officers, descended onto the property at 9.10am yesterday.

They tried to get in through the back but found the doors tightly-locked behind metal shutters.

They eventually had to snip open the shutters on the shopfront, and were let in to the former nail salon by the landlord. They found that the doors were not only locked, but were also wound tightly shut with cable and wire.

Sergeant Cliff Tomkinson, who led the raid: “That meant we were reluctant to touch the handle in case it was electrified. That often happens with these factories – it’s often to deter rival dealers who might break in.”

The officers filed up the steep, narrow staircase into the flat above, which contained hundreds of cannabis plants lined up in every available space.

However, they deduced the suspect must still be close by after exhibits officer PC Mark Tallis noticed the kettle was still warm.

A short search and a tip-off from a member of the public later, and PC Kevin Sinar found a man, believed to be Vietnamese, hiding on the roof. He was arrested and taken to Brierley Hill Police Station for questioning.

Sgt Tomkinson said it is believed the landlord had rented the flat out to a third party two or three months ago. He added: “This is a very professional set-up.

“They’ve got good plant pots, a good irrigation system, a really good clean air system – it’s not surprising nobody suspected anything much.”

Rob Mantle, owner of Coffee Uno next door, said the shop had been standing empty for around 18months.

“I never suspected anyone might be living there. Congratulations to the police, that’s all I can say.”