Thieves who stripped £20,000 worth of lead from a Brentford museum rooftop could end up putting it out of business after a string of burglaries.

Staff at Kew Bridge Steam Museum spotted a section of the roof was missing and called police – but before officers could arrive to investigate thieves struck again the next night, stealing more lead.

Director Ernest Buchner said although the theft would not stop planned activities at the museum, staff were finding it hard to cope and the listed building could be forced to close its doors for good if thieves struck again.

He said: “I just want all these thefts to stop, last year someone raided the giftshop and we had another theft before that. If this keeps happening again and again and again we will go out of business.”

Staff at the museum believe the raid was a calculated theft with the culprits staking out the museum days before.

Mr Buchner said: “I think they were casing the joint, this was a professional job. There must have been a few of them to carry the lead and transport it away.

“I am disgusted. They have destroyed a part of England’s heritage. This roof was irreplaceable and a part of history has been lost. I feel a lot of disappointment in my fellow man right now.”

The building, in Green Dragon Lane, is owned by Thames Water, which has agreed to repair the roof, and Mr Buchner said he was looking into claiming £20,000 in insurance for the thefts on August 11 and 12.

Kew Bridge Steam Museum, has the largest collection of steam powered active pumping engines in the world, including the largest operating single cylinder Cornish beam steam engine anywhere.

Founded in 1972 by a group of volunteers in the former Kew Bridge Pumping Station of Thames Water, the museum relates the story of London’s supply of fresh water from Roman times to the late 20th century.

Mr Buchner said staff were looking into improved security measures.

A police spokesman said officers were investigating the thefts and appealing for witnesses.

Contact Hounslow CID on 020 8247 6160.