Yes, you can extend in Colerne, but the planning department will be involved from the start. Ninety buildings are listed. The old core is a conservation area. The whole village sits in protected Cotswold landscape. Your neighbours clearly aren't put off, because they apply constantly.
Colerne has 90 listed buildings: one Grade I, one Grade II* and 88 Grade II. Listing covers the whole building, inside and out, plus fixtures and often boundary walls. Any change that affects its character needs listed building consent on top of any planning permission. That includes replacing windows, knocking through a wall or changing a roof covering. Most of the 90 are Grade II, the most common grade, but Grade II still means the council gets a say over your windows. Buy a listed house and you're its custodian first and its owner second.
There's one conservation area, named after the village itself. Inside it, the council controls changes that affect how the area looks. That covers demolition, works to trees, and alterations visible from the street, which are the ones owners most want to make. The whole village also lies within the Cotswolds Area of Outstanding Natural Beauty, where some permitted development rights are narrower than they would be elsewhere. The front of the house is where the rules bite hardest. A modest extension at the back, out of sight of the lane, is a different conversation.
None of this has stopped anyone trying. Planning records show 871 applications in and around Colerne between April 2024 and June 2026, including 356 in the last twelve months. That's steady traffic, not a village frozen in amber. People here are adding rooms, converting outbuildings and swapping windows, and they're doing it through the proper channels because the proper channels are unavoidable.
In practice, a post-war semi outside the conservation area and not listed is the easiest home to change. It still has permitted development rights, subject to the protected-landscape limits, so a rear extension or loft conversion may not need a full application. Anything listed, or inside the conservation area and visible from the street, should be treated as needing consent until the council confirms otherwise. The cheapest step is to find out which of those categories a house falls into before making an offer, not after the builder has been booked. A pre-application enquiry costs far less than an extension you have to take down.
Freedom to alter a home in Colerne is middling. Ordinary houses can grow with the usual paperwork. Listed and conservation-area homes change slowly and only with the council's agreement.