"It follows from all that we have said that in our Judgment the Preliminary issue raised here which we shall continue to refer to as the Henderson v Henderson point must be resolved in favour of Waltham Forest. In reaching that conclusion we are mindful of, not only this, but a number of other cases in which successive applications in relation to discrimination have been lodged by persons who remain employees of the same employer, leading to multiple Hearings before Employment Tribunals and sometimes a labyrinth of Tribunal Hearings and Appeals arising out of the same history."