Complex sentence: This is the earliest date to be found on any windmill in the British Isles; it should be remembered that such a structure would have had to have frequent repairs made to it, so it is quite possible the mill predates 1627.
Split into simpler sentences: This is the earliest date to be found on any windmill in the British Isles. It should be remembered that such a structure would have had to have frequent repairs made to it, so it is quite possible the mill predates 1627.