Yes, most Benson homes can be extended, provided they are not in the old core. Most of the village is post-war housing that nobody thought to protect. The older centre is another matter, with a long list of listed buildings and conservation boundaries close by. The neighbours are applying for planning permission at a steady rate. What you can do depends on which half of the village the house is in.
Benson and its immediate surroundings hold 124 listed buildings. Four are grade I, four are grade II* and 116 are grade II. Listing covers the whole building, inside and out, along with anything fixed to it, so changing a listed house usually needs listed building consent from the council on top of any planning permission. Grade II covers almost all of them, and grade II still applies to the interior, the windows and the outbuildings. The grade I and II* buildings are the ones where nobody should expect to change much at all.
Three conservation areas lie within the same surroundings, at Benson, Ewelme and Preston Crowmarsh. Inside a conservation area, demolition needs consent, works to trees need notice, and some of the smaller extensions and alterations that elsewhere go ahead without an application become a matter for the council. The houses inside those lines look as they do because someone has spent decades making sure they stay that way.
One scheduled monument falls within the area. That is the strictest level of protection, and it matters mainly to anyone whose land touches it. The ground here holds more history than the monument list shows, though. When a housing site at the corner of St Helen's Avenue and Church Road was excavated, it turned up Neolithic pits, a possible Bronze Age roundhouse and Saxon sunken-floored buildings. Anyone planning a basement in Benson should allow for finding someone else's.
In and around Benson, the council's register lists 1,349 planning applications between April 2024 and June 2026, 595 of them in the last twelve months. People here plainly do extend, convert and rebuild, and they do it in volume. In a village where most residents take a close interest in what their neighbours are doing, every one of those applications had an audience.
For most of Benson, the post-war semis and detached houses that make up the bulk of the village, the ordinary household rights to build modest rear extensions, outbuildings and some loft work without a full application should apply as they do elsewhere, subject to the usual limits. Those rights narrow inside a conservation area and largely stop for a listed building, where almost any change of substance needs consent. South Oxfordshire District Council's planning records will show whether a particular house is in a conservation area, whether it is listed, and what earlier owners asked for. A refused extension from a decade ago is worth knowing about.
Benson is middling on freedom to extend. Most of the village leaves you plenty of room, and the old core, inside its conservation lines and around its listed buildings, gives you almost none.