Two people being held in custody managed to swallow drugs despite being searched by police officers, a new report has found – as inspectors raise “serious safety concerns” about the way Thames Valley Police treats detainees.

Her Majesty’s Inspectorate of Constabulary and Fire & Rescue Services (HMICFRS) and Her Majesty’s Inspectorate of Prisons carried out custody inspections at eight police stations including High Wycombe and Aylesbury in February this year.

While their report was “generally positive”, inspectors said they had serious concerns about the way detainees were searched – with some able to retrieve hidden items while in the cell, like drugs and other items that could cause harm – even though they had been searched.

Inspectors said there were “fundamental gaps in practice” which posed a “significant” risk to the safety of those being detained.

Some people being held were found with dangerous items after undergoing initial and strip searches and inspectors witnessed two detainees swallow drugs while in custody, forcing them to go to hospital.

Officers who were conducting cell watches were sometimes “inadequately trained” and some were on watch for long periods without suitable breaks.

Inspectors added: “Cell call bells were routinely left either mute or set to a low volume, with custody staff having to rely on a flashing computer screen to know when a bell had been pressed. We observed times when bells were left unanswered for too long.”

Some cells – including some at High Wycombe police station – were deemed to be “far too cold” and shoes were routinely taken away from all those being detained, which inspectors said was “disproportionate”.

Officers also did not record all instances where force was used in its custody suites and many did not submit individual ‘use of force’ forms after they had used force against a detainee.

Concerns were also raised about the dignity of those being held, with some forced to ask for toilet roll or sanitary products and having to walk around the custody suite without any shoes on, even though other supplies were available.

Inspectors saw a female detainee complain that she had tried to request sanitary items but did not get it, resulting in her clothes being soiled – which inspectors said was “degrading”.

Despite their concerns, inspectors said people taken into custody by Thames Valley Police were held in generally clean and well-maintained cells and were treated respectfully.

They also said there was a “clear commitment to providing effective custody services, with well-trained custody sergeants”.

Responding to the report, Superintendent Katy Barrow-Grint, from Thames Valley Police, said: “I will be reviewing the findings of the report closely and working with colleagues and partners across the Thames Valley to ensure that, where areas have been identified for improvement, we will act to address these.

“I am pleased that the report has recognised the progress we have made since the last inspection in particular in our health services which were found have improved significantly.

“Custody staff dealt well with many challenging detainees, and often de-escalated situations effectively to avoid using force.

“We will act on any learning from this report and welcome the recognition of the progress made since the last report and the findings of this inspection which are generally positive.”