Yes, and plenty of people are doing it right now. The listed stock is a minority of the town rather than the rule. One conservation area covers the middle of it. Hundreds of applications have gone in over the past couple of years, which is not the profile of a place that says no. The thing most likely to complicate your extension here is not the planners. It is what the house is standing on.
There are 106 listed buildings across the area: 2 at grade one, 2 at grade two star, and 102 at grade two. Listing covers the whole building rather than the pretty side of it, which is the detail owners tend to discover after they have paid an architect. Work that affects the building's character needs consent, and character is assessed by someone whose job is the building rather than your plans for it. That is not a refusal. It is a longer, costlier and more specific conversation, and it applies to a minority of homes here rather than the general run of them.
One conservation area sits over the town. Designation brings extra control over external alteration and a higher bar for anything visible from the street, on the basis that the appearance of the area is a shared asset rather than a private one. The practical effect is that the same rear extension can be a form-filling exercise on one street and a design negotiation on the next.
Two scheduled monuments fall within the area. That is the strictest tier of protection in the system, and for most households it is irrelevant. For anyone whose land runs up against one, it is the first question rather than the last.
The register is busy. There have been 491 planning applications across the area between April 2024 and July 2026, with 191 of them in the last twelve months. That volume is the honest answer to whether homes get altered around here, and it says the paperwork is a routine cost of ownership in an old town rather than a rare adventure.
The ground is where the money goes. The geological survey puts the area in shrink-swell class 3, and every postcode in the place reaches it, which is what clay does: it takes on water in winter and gives it back in a dry summer, and the ground moves either way. For an extension that means foundation depth designed for the conditions rather than lifted from a standard detail, a structural engineer involved before the drawings are finished, and a hard look at any mature tree near the trench line. The other hazards are quiet by comparison, with soluble rocks, collapsible and compressible ground and running sand all sitting in the lowest class.
So the sequence for most houses is ordinary. Unlisted and outside the conservation area, a rear extension is a matter of checking what rights the property has rather than making a case. Listed, or inside the conservation area, and consent leads and the design follows the building. In both cases the ground investigation is the line item people leave out of the budget and then meet at the bottom of a hole.
Freedom to alter a house here lands somewhere in the middle. There is no blanket restriction and no shortage of neighbours getting work approved, but a fair slice of the most appealing stock carries conditions, and the clay applies its own quiet veto to a cheap set of foundations. Buy something plain for a free hand, buy something old for the address, and price the difference before exchanging rather than after.