Overturning the EAT, the Court of Appeal has construed a contractual clause in a collective agreement, which provided that the employer would increase pay by one of two possible percentages, as requiring the employer to pay the higher of the two. It was fanciful that the unions would have agreed that the employer could choose between them and this must have been obvious to the employer. It would have been nonsensical for the clause to provide for a maximum pay increase (which would be the effect if the employer could choose), rather than a minimum. (Anderson v LFEPA)
Of course, best practice is to avoid ambiguity by careful drafting!