Dct_Mopas
It most certainly now can, as the law has changed to say it can in this special case - further, it says that it is an employee's right to do so, not simply an optional permission. Contracts cannot impose terms that go beyond the law - if a law changes, they must change to reflect that change. Whether or not a company obeys the law as it now stands (or is even aware of the change) is another matter - as is the consideration of whether a person who's been sat on their arse for a year really needs to carry holidays over.
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As for what the exemption is intended to cover, it matters not. It applies to everyone, in whatever circumstance.