Yes, Marlow Bottom is one of the easier places to extend a house. Only three buildings are listed. None of the village is in a conservation area. Neighbours file plans all the time. The paperwork here is light, but the ground is not.
There are 3 listed buildings in Marlow Bottom, all grade II, with none at grade I or grade II*. Listing means any change to the fabric of one of those three, inside or out, needs listed building consent on top of any planning permission, and the council takes that seriously. Everyone else is dealing with ordinary planning. In a valley built mostly after the war, the heritage register has very little to say.
The planning records for the area logged 1,185 applications between April 2024 and June 2026, and 503 of them in the last twelve months. Whatever the outcome of each one, that volume shows people here alter their homes as a matter of course. In a valley where most houses already have four bedrooms, someone is always applying for a fifth.
The constraint is underground. The British Geological Survey's hazard mapping puts shrink-swell clay at class 3 across about 92% of postcodes, and soluble rock at class 3 across all of them. Clay that swells when wet and shrinks when dry moves foundations, especially near thirsty trees, so an extension here usually means deeper footings than a builder from a sandier county would expect, and a structural engineer's view at the start. That adds cost and design work. It does not stop anyone building. The planners will let you build out, and the clay will decide how far down you have to go first.
In practice, many rear extensions and loft conversions on ordinary houses can go ahead under permitted development, the national rights that need no planning application. The whole village is inside the Chilterns Area of Outstanding Natural Beauty, though, and some of those rights are narrower in such areas. A lawful development certificate from Buckinghamshire Council settles whether a particular scheme needs full permission, and it costs far less than a refusal.
Freedom to extend is one of Marlow Bottom's real strengths: no conservation area, an almost empty heritage list, and nothing much in the way except the clay.