"The exception to the doctrine in Polkey[1988] ICR 142 which the tribunal erroneously invoked at paragraphs 55 and 57 of its decision has no application in a case where the employee is entitled to insist that the employer must honour a contractual obligation to follow a particular disciplinary procedure: Stoke v. Lancashire County Council[1992] IRLR 75 , CA, per Dillon LJ ( with whom McCowan and Nolan LJJ agreed) at page 77, paragraphs 20-24; Cabaj v. Westminster Council[1994] IRLR 532 , EAT, per Mummery J (P) at page 553-4, paragraphs 13-18."