Yes, slowly, after a conversation with the conservation officer. The cathedral city carries about 560 listed buildings, four named conservation areas, and fifteen scheduled monuments. Permitted development is mostly a memory once you cross a heritage line. Most non-trivial plans need formal consent. The freedom-to-extend score sits at the bottom of the scale, and the score earns it.
The listing density is the headline. There are around 560 listed buildings inside the postcode area: sixteen at Grade I, thirty-five at Grade II starred, and the rest at Grade II. A listing applies to the building rather than to a planning category, which means anything that affects character, fabric or external appearance needs listed-building consent on top of any normal planning permission. That covers windows, doors, render, roof coverings, internal partitions in many cases, fitted joinery, fireplaces, the lot. The Grade I and Grade II starred buildings are the most heavily constrained, and the Grade II buildings are the ones most owners actually live in, which is where the daily friction lives. Owning a listed property here is a relationship with the planning office rather than a transaction at exchange.
Four conservation areas sit inside the postcode footprint: Chichester itself, Graylingwell, Fishbourne and Dell Quay. A conservation area designation does not freeze a house, but it does strip back many of the permitted-development rights that a non-designated property would carry. That can mean planning consent for changes to the front elevation, restrictions on cladding and render, controls on satellite dishes, and limited scope for roof additions. Add fifteen scheduled monuments scattered across the same footprint, and the area starts to look less like a town to live in and more like an open-air gallery of regulated objects. A buyer who likes the look of a particular Georgian frontage should assume the frontage is the most protected part of the deal.
In practical terms, permitted-development assumptions that work in a 1990s housing estate elsewhere in the country do not work here. A loft conversion, a side return, a glazed gable, a heat pump on the boundary wall, a charging point on the kerbside, a different paint colour: any of them can require an application, and the answer depends on whether the property is listed, in a conservation area, near a scheduled monument, or all three. The right move is to talk to the planning officer and the conservation officer before the survey, not after the offer. Budget for surveys, heritage statements, and a slower decision than a non-heritage area would deliver. The work, when it lands, lands properly. It also lands more slowly and more expensively than the same project would somewhere with fewer regulators in the room.
So: not freely. The freedom-to-alter score here is the lowest the scale runs, and the reason is the heritage density that makes the city worth visiting in the first place. The houses you can change quickly are not the ones you came for. The ones you came for are not the ones you can change quickly.