Under the agreement, the company agreed to sell by 25 April next year the 21 Welcome Break sites it took on following its pounds 3.9bn takeover of Forte, concluded in February.
Granada also agreed to abide by price controls on its services and food in the period leading up to divestment, in the form of a revenue cap set by reference to prices on 21 March. The deadline, originally set at 15 months from the date of the undertakings, was also changed. The undertakings were amended following representations by rival operators, who had accused Granada of abusing its near-monopoly on Britain's motorways.
The most likely buyers of Welcome Break are the brewers Whitbread or Bass, the French hotels and services company Accor or a fast-food company, possibly McDonald's. Burger King has already reached an agreement with Granada to franchise its restaurants on Granada motorway sites.
Charles Allen, Granada's chief executive, said: "My preference is to move very quickly."