Maximum height of eaves on single storey when 2m away from neighbour

ey143

What is the maximum permitted height of the eaves on a single storey extension when applied for under permitted development when the extension is 2m AWAY from neighbouring properties.

The interactive planning portal is confusing as it states that it cannot be more than 3m when you are within 2m. Why doesn't it state what it is when you are away from 2m of the boundary?

A local architect tells me it is still 3m but on another DIY forum they said it is unto 4m, which is also the maximum height of a single storey.

Also when the ground is sloping up and away from the extension (towards the end of the garden), I am getting conflicting views on whether you take the lower or higher natural ground height.

Thanks.