David Ross, the disgraced businessman who failed to declare using shares to secure personal loans, has resigned as chairman of Cosalt, the safety equipment specialist.

Mr Ross's resignation is the fifth this week. The board of Cosalt, the company his grandfather bought almost 60 years ago, have asked him to step down as chairman, but remain on the board.

Mr Ross has already quit as deputy chairman of Carphone Warehouse, the mobile phone company he founded with schoolfriend Charles Dunstone.

He has also quit as an adviser to Mayor of London, Boris Johnson, on the 2012 Olympics, as chairman of National Express, and from the board of Big Yellow Group, the storage company.

Cosalt said today: “Whilst the board accepts that Mr Ross apparently breached certain regulations, it is currently of the view that he did so wholly unintentionally and that this in itself does not require him to step down from the board altogether.”

Times Recommends

• Minister in talks with Saudis to protect creditors
• Premier Inn hits back in £29-a-room row
• Bankers hit back at 'populist' bonus supertax