Murco’s US parent business is set to sell its UK business this month to a private equity firm, Greybull Capital, for more than $500m, according to sources close to the negotiations.

Murphy Oil has had a long-stated aim of selling off its UK business and last month a spokeswoman said: "Discussions with regard to the sale of the Murco UK business by its US parent, Murphy Oil Corporation, are ongoing and are at an advanced stage."