Brandon LJ said: ‘With regard to ignorance operating as a similar impediment, I should have thought that, if in any particular case an employee was reasonably ignorant of either (a) his right to make a complaint of unfair dismissal at all, or (b) how to make it, or (c) that it was necessary for him to make it within a period of three months from the date of dismissal, an industrial tribunal could and should be satisfied that it was not reasonably practicable for his complaint to be presented within the period concerned.
For this purpose I do not see any difference, provided always that the ignorance in each case is reasonable, between ignorance of (a) the existence of the right, or (b) the proper way to exercise it, or (c) the proper time within which to exercise it. In particular, so far as (c), the proper time within which to exercise the right, is concerned, I do not see how it can justly be said to be reasonably practicable for a person to comply with a time limit of which he is reasonably ignorant.
While I do not, as I have said, see any difference in principle in the effect of reasonable ignorance as between the three cases to which I have referred, I do see a great deal of difference in practice in the ease or difficulty with which a finding that the relevant ignorance is reasonable may be made. But, where a person is reasonably ignorant of the existence of the right at all, he can hardly be found to have been acting unreasonably in not making enquiries as to how, and within what period, he should exercise it. By contrast, if he does not know of the existence of the right, it may in many cases at least, though not necessarily all, be difficult for him to satisfy an industrial tribunal that he behaved reasonably in not making such enquiries.’
Dennning L MR said: ‘It is simply to ask this question:- Had the man just cause or excuse for not presenting his complaint within the prescribed time? Ignorance of his rights – or ignorance of the time limit – is not just cause or excuse, unless it appears that he or his advisers could not reasonably have been expected to have been aware of them. If he or his advisers could reasonably have been so expected, it was his or their fault, and they must take the consequences.’
Brandon LJ, Dennning L MR
 ICR 52,  IRLR 499
Updated: 15 May 2022; Ref: scu.346607