It has also called for legal action to be taken against any companies, contractors or subcontractors who allow "these dangerous practices to occur".
Unite received a tip off from local resident and former Labour London Assembly member Murad Qureshi and investigated the construction site at Abercorn Place estate in St John's Wood, north London, which is owned by the company Kunta Kinte. The 1950s former council build is known as the Cricketers because its three blocks -- Bradman, Warner and Verity -- are named after famous pre-second world war cricketers.
It found that a group of non-EU nationals were involved in renovating several apartments on the Warner block. In December 2017, the Daily Mirror newspaper reported that Kunta Kinte, which is run by Mukurrum Sattar with his relatives and their firms, owns the leases to 30 of the 35 flats in the three blocks.
In early June, Unite's regional officer Paul Lomax visited Abercorn Place and observed a green sofa, clothes hanging on a washing line, several mattresses and bedding, along with food containers at the site.
He wrote to Westminster Council's chief executive Stuart Love and copied in Westminster's building control department and the HSE to raise his concerns and urged both organisations to take urgent action as the workers were potentially in serious physical danger.
"Workers must never be allowed to live on a construction site, the potential for serious injury is huge and there are also massive occupational health issues that need to be considered," he said.
"It is absolutely imperative that Westminster council and the HSE immediately take responsibility for this dangerous site and ensure that no one is living on this or any other building site."
Lomax said legal action should be taken against any companies, contractors or subcontractors that allow these dangerous practices to happen.
Unite told IOSH Magazine that Westminster's building control department had responded and informed Unite that it had no powers to control work practices on the site. It added that it could only enforce building regulations and directed the union to the HSE, which has powers under the Construction (Design and Management) Regulations 2015 to enforce safe working practices.
A spokesperson from the HSE told IOSH Magazine: "HSE has visited the Warner House site twice recently. The first occasion was as part of our campaign of inspection visits in London. During this visit a prohibition notice was served preventing all work on site. Other enforcement action to address safety management matters was also taken.
"The second visit was made on 4 June in direct response to a complaint received and inspectors were told that there were no workers sleeping on site. Inspectors found no evidence of workers sleeping on site at either visit."
The HSE said that it would undertake follow-up work with the principal contractor.
In December 2017, the Hampstead and Highgate Express reported that Labour councillor Paul Dimoldenberg had called for an inquiry after the freehold of the entire site and almost all the properties had been transferred to Kunta Kinte, which was overseeing the renovation work.
Dimoldenberg wrote to Westminster council's planning and housing chief Ed Watson and asked how Kunta Kinte had bought up enough leaseholds to trigger a tenant buy out of the estate. The Hampstead and Highgate Express reported that in housing law, tenants can acquire a building's freehold if 50% opt in. Tenants are barred from doing so if they own more than two flats.
