Erlestoke Prison near Westbury is winning its battle against drugs, according to a report published by the prison’s independent monitoring board.

It is the most encouraging vote of confidence prison authorities have had from the volunteer monitors for some years as problems of drugs, challenging behaviour and poor conditions have been successfully addressed.

Prison governor Andy Rogers welcomed the report, published on Thursday, and said that he was determined to make Erlestoke Prison drug free.

He said: “We tested a third more prisoners than in the previous year and the number of positive tests was much lower.

“I won’t tolerate drugs in my prison and it will be drug free as soon as is possible. So far this month we have had no positive tests at all and I hope that is going to continue.”

Prisoners can be very cunning about smuggling into the prison drugs and mobile phones – with which drugs are ordered.

The prison recently acquired a second drugs sniffer dog and the amount of seizures of drugs increased.

It also has a BOSS chair – bodily orifice security system – in which prisoners are sat down and a high intensity metal detector finds if they are carrying a mobile phone inside them.

Drugs are often smuggled in greetings cards. The front of the card is cut away and drugs secreted behind it, or made into a paste and smeared over the back of the card.

Sniffer dogs check all mail delivered to the prison each day.

The prison’s training regime also came in for praise. The prison was graded as “good” by the education watchdog Ofsted, the second highest category, in a recent inspection. More than 50 per cent of all prisoners in British jails can barely read and write but Erlestoke has a good record of adult literacy training.

There was also good news for the monitoring board regarding the much criticised Wren Unit. This 1960s building has been very dilapidated in recent years and had created a very bad impression with new arrivals who had traditionally been received there.

Staff and prisoners together have redecorated it and there are now firm plans to demolish and rebuild it. It has been put out to tender.

Simon Petchey, who is standing down as chairman of the monitoring board, was fulsome in his praise of governors and staff.

He said: “The board commends the commitment, professionalism and dedication of the two governors (Mr Rogers and his predecessor Doug Moon) in charge of the prison during the year, their management team and all their staff.

“They initially managed to maintain a generally humane and progressive environment despite severe financial constraints, and latterly have started to take the prison forward with new energy and vision."