Islington Council is checking up on 4,000 private developers in the wake of the Grenfell Tower disaster.

The town hall has reminded all owners of “tall buildings” – 18m or six storeys high – to carry out fire safety checks on all ACM cladding systems, which are widely thought to have caused the tragic Grenfell blaze in west London last month.

In all, planning service director Karen Sullivan has written to about 4,000 private developers who have applied for planning permission to Islington in the last 15 years. The request will only apply to a minority of property owners, as most buildings will not be classified as “tall”. Ms Sullivan has also written to everyone who operates student accommodation in the borough.

The council’s action on private owners follows swift assessments of its own tower blocks. Only one, Braithwaite House near Old Street, was found to have ACM cladding, most of which has been removed.

Ms Sullivan said in her letter: “On June 20, the Department for Communities and Local Government (DCLG) wrote to the owners, landlords and managers of private residential blocks. DCLG asked that fire safety checks are carried out on all ACM cladding systems on tall buildings. DCLG will meet the costs of the initial tests. If you undertake the tests offered by DCLG and find anything of concern, I would be grateful if you could let me know.

“Please can you also check to ensure that your fire risk assessments are up to date. In particular, your fire risk assessments should take account of any authorised or unauthorised alterations that have been carried out to the cladding systems since they have been installed. As you will no doubt be aware, even relatively minor alterations to these systems can greatly compromise their ability to resist the spread of fire.”