Grandmother Margaret Waite had the surprise of her life when she was sitting in her kitchen drinking a cup of coffee and in walked a policeman looking for a drugs suspect.

But it could have been worse for the officers said that, had the door been locked, they would have had to break it down.

They were red faced when Mrs Waite, 69, pointed out that they were in the right street – Rhyls Lane at Lockeridge – but at the wrong house.

She agreed to let one officer go upstairs to have a look around because they were concerned, she said, that the man they were looking for might have been staying there.

The officers had a warrant issued under the Misuse of Drugs Act to search Mrs Waite’s home because suspect parcels had been delivered there but they were addressed to her neighbour and she used to take them from the postman and put them in his porch.

Mrs Waite said: “I did have a few parcels come here some months ago with my address but for the man next door so as soon as I was handed them by the postman I would go and put them in his porch. I did not even notice where they had been sent from.”

Police then went next door to No 2 Rhyls Lane and found the man they were looking for, and seized 10,000 tablets believed to have been imported from China and India.

A 28-year-old man, who was later released on bail until January 4 pending further police inquiries, was arrested on suspicion of importation and illegal supply of controlled drugs and money laundering.

Police raided the house on Friday after receiving information from the UK Borders Agency and a UK pharmaceutical company that the subject was suspected of importing counterfeit prescription drugs classified as a Class C drug under the act.

It is understood a Royal Mail investigation team was also involved in the operation.

Mrs Waite, the widow of a gamekeeper, was sitting in her kitchen at about 8am on Friday when the police officer walked in through her open back door.

She said: “He said he had only come around to the back door by chance and if it had not been open they would have had to break it down.”

Mrs Waite said the officers were very friendly and apologetic and later that day policewoman PC Sarah Watts went to her house and apologised.

Police said they did have warrants to search both houses but added: “It was quickly established by officers that the neighbouring house to the subject had no involvement in the case.”

PC Watts, community beat manager for the Kennet Valley villages, said: “I would appeal to anyone who has any information about the supply or use of drugs within their community to come forward so that we can work together to disrupt illegal activity concerning drugs.”