Ford has started an internal investigation into why its president Sir Nick Scheele tried to push all its advertising work to advertising agency WPP – run by his friend Sir Martin Sorrell.

According to a report in The Guardian, the relationship between the two men – which goes back many years – has become closer since Sir Nick's son, James, joined WPP as a New York-based account manager of the group's Young & Rubicam offshoot.

The inquiry is centred on a directive from Sir Nick, Ford's second most senior executive, to his staff after a New York meeting in November between himself and Sir Martin.