 This is because some judges have taken the view that there was not sufficient "control" or "mutuality of obligation" to establish a contract of employment.What those judges have meant by "mutuality of obligation" is that the terms of the contract, especially an obligation to work or not work at any given time and the promise of work in future, were not reciprocal enough.So in "O'Kelly v Trusthouse Forte plc" [1983] ICR 728, Sir John Donaldson MR held that some waiters who were hired through an agency to do dinner functions were not "employees" (either of the function hall or the agency) because they did not, technically, have to turn up to work for a shift, and they could be sacked at any time.