The council. They know about the shed, they've had me abide by their rules and I have done, and they'll come out when it's finished.Who will be measuring? If you've done it under PD then the council won't be bothering you unless someone complains. And I believe you're allowed to take the level from the highest bit of ground adjacent to the shed (so if you're on a bit of a slope then 2.5 at the top of the slope would be OK).
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