Slough’s tallest block of flats is covered in an unsafe cladding system with combustible insulation, developers have confirmed.

Residents of the 15-storey Lexington Apartments building contacted the Observer after flammable cladding was found at the nearby Mosaic Apartments which caught fire last month.

One resident, Sarath, told the Observer that, with a firefighters’ lift also out of order at the apartments, the situation was an ‘accident waiting to happen’.

Royal Berkshire Fire and Rescue Service (RBFRS) confirmed that it was first told the cladding on Lexington Apartments needed remediation work in 2020. But four years later building manager One Housing has yet to replace it.

Although the aluminium panels are not flammable the insulation behind them - which the government says forms part of a building's 'cladding system' - does need to be replaced with a non-combustible type.

Building owners also said the system's cavity barriers - which are meant to seal off gaps during a fire to stop it spreading -  also need remediation work.

A spokesperson for One Housing said the company was working to remediate the cladding ‘as quickly as possible’ – but appeared to suggest it was prioritising ‘higher risk’ buildings elsewhere.

The spokesperson said: “Building safety remains a top priority for us as a commitment to the safety and security of our residents.

“We have invested approximately £100m in cladding remediation works in the past few years and have set aside a total of over £300m to complete the work. We will continue to do all we can to help put things right.”

“Our remediation programme timeline is based on risk, and we are working through the highest-risk buildings first.

“We apologise to residents at Lexington who want remediation completed quickly and we continue to work as quickly as possible to complete the necessary building works.”

A spokesperson for RBFRS said the fire service was working with One Housing on fire safety measures. It said it was ‘made aware’ that the cladding on Lexington Apartments needed replacing in 2020, and that it had been told this work ‘has been planned’.

The fire service said: “The cladding is on the exterior of the whole building; however, the ground floor at the front of the shop area has been removed and replaced. The person responsible for the building has informed us that the remaining remedial work has been planned .

“We are working directly with the person responsible for the building to assist them in meeting their legal duties. As a result of this, they have now added additional interim fire safety measures, such as providing extra staff to continually patrol the building.

“The purpose of this is to detect a fire, raise the alarm, and manage any evacuation, if needed. The building has also adapted its evacuation strategy to simultaneous evacuation during this period, until remediation works are complete.”

The confirmation comes as a firefighting lift – which firefighters can use to send equipment to higher floors during a fire – is out of order.

RBFRS said this could ‘delay our crews getting to the higher floors’ in the event of a fire. It also said it had not initially been notified of this by One Housing.

However One Housing says it did notify the fire service, and that the lift is out of order because firefighters had to cut it open after it got stuck with people inside. It said ‘large scale repairs’ were now needed.