Yes, but the paperwork gets a vote. The wider area holds nearly three hundred listed buildings. Three conservation areas sit within it. The neighbours file planning applications all year round. Assume someone will have an opinion on your extension before the builder does.
Historic England's list puts 282 listed buildings across the Horam area. One is Grade I, 14 are Grade II* and the other 267 are Grade II. Listing covers the whole building, inside and out, and any alteration that affects its character needs listed building consent on top of planning permission. That includes the windows, the staircase, the fireplace nobody likes and the render somebody regrets. Doing the work first and asking afterwards isn't a shortcut. It's a criminal offence with a bill attached. If the house you want is on the list, it's partly the list's house.
Three conservation areas fall within the area: Old Heathfield and Cade Street, Rushlake Green, and Warbleton. In a conservation area, changes that would pass without comment elsewhere can need permission, and demolition, trees and anything visible from the street get extra scrutiny. Your house doesn't have to be listed to be looked at. It only has to be in the right street.
There are also 2 scheduled monuments in the area, the strictest tier of heritage protection. They matter mainly if you're buying land next to one, where digging needs more than planning permission.
The neighbours clearly aren't put off. Across the area, 1,959 planning applications were lodged between March 2024 and June 2026, including 839 in the most recent twelve months. That's plenty of people wanting to build, extend or alter, and plenty of consultation letters landing on doormats. Extensions happen here. They just come with forms.
One listed building in the area sits on Historic England's Heritage at Risk register. That means it's in poor condition and its repair is being watched, and it may qualify for grant support. It's a problem for whoever owns that building, not a hazard for the buyer of an ordinary house down the lane.
In practice, check two things before you offer. First, whether the house is listed. Second, whether it's in one of the conservation areas. If it's neither, ordinary permitted development rights may cover a modest extension, though the council has the final word on what qualifies. If it's either, budget for applications, drawings and time, and treat the loft conversion in the estate agent's patter as an idea, not a fact.
Freedom to alter a home here is limited: fine for the unlisted house outside a conservation area, slow and costly for the rest. Most buyers should plan on consent, not on permitted development.