Several employees and ex-employees from contractors Rydon, Harley Facades and the Kensington and Chelsea  Tenant Management Organisation are among those who have made the request for immunity to give them ‘freedom to tell the truth’.

Inquiry chairman Sir Martin Moore-Bick said: “Very recently I have been advised that when they are called to give evidence next week, many of the witnesses involved in the design and choice of materials will claim privilege against self-incrimination as a reason for not answering questions.

“This development has caused me a little surprise because hitherto there has been the fullest cooperation within the inquiry both in the firm of given written statements and provision of documents.”

He revealed an application was made last night by a number of counsels for various core participants in the inquiry next month.

“What they are asking me to do is apply to the attorney general for an undertaking that nothing said by a witness in answers to questions in the inquiry will be used in furtherance of prosecution against them.”

It would allow them to have the “complete freedom to tell the truth without any concern for the future”, he said.

The application will be heard on Thursday afternoon.