"It is quite a different matter if the tribunal is able to conclude that the employer himself, at the time of dismissal, acted reasonably in taking the view that, in the exceptional circumstances of the particular case, the procedural steps normally appropriate would have been futile, could not have altered the decision to dismiss and therefore could be dispensed with. In such a case the test of reasonableness under section 57 (3) [nowsection 98 (4) of the Employment Rights Act 1996 ] may be satisfied."