Longer term plan - not sure if it's likely to need PP?

It's hard to ask our council - you can't just pop over to see a bloke,
unlike the building inspector and they charge to even answer a letter
(tightarses!).

I have read that "engineering works" (meaning non de-minimis earthworks
in the garden) are not automatically considered as permitted development.

I want to regrade (change the level) of the front garden but chopping a
300mm lump off the high part and pushing it down the slope to the low
side, raising that no more than 200mm.

That seems like no one would care too much (decking under 300mm can be
permitted development, so if I am gaining 300mm I'm not going to be
annoying any overlooked neighbours).


But the bigger earthwork one will be cutting into a bank towards the
side road (I'm on the corner).

This bank is 1.2m above the level of the house ground floor and drive.
so the bank is cut back to fit the house and a path in.

I want to cut into this bank about 3m towards the road and 3-4m wide to
make a sunken patio area. Apart from a small wall or rockery around the
top edge to stop people falling down into it from the lawn, there will
be no works above ground level.

I might even go down 300mm as well to make it more hidden (the far end
of the garden is even further downhill so I should be able to arrange
drainage of the sunken area).


So is that *likely* to need PP?


I have trawled local PP applications for the last couple of years and I
can find no application for purely landscaping reasons... But several
sites suggest it is a grey area and might require it...


Cheers,

Tim