Yes, in most of Hitchin, though the town keeps more of its past under protection than a buyer planning a big extension might like. Hundreds of buildings are listed. Eight conservation areas cover the town and its villages. Neighbours file planning applications by the thousand. Extending is normal here, and so is asking first.
Historic England's list holds 224 listed buildings in and around Hitchin. Two are Grade I, 14 are Grade II* and 208 are Grade II. Listing covers the whole building, inside and out, so on a listed house even a new window, an internal wall or a change of roof covering needs listed building consent from the council on top of any planning permission. Most of Hitchin's housing is unlisted, and the 224 are spread through the old centre and the villages around it, which is where a buyer with a period house should expect to meet the rules.
Eight conservation areas fall across Hitchin and its edges: Hitchin itself, Butts Close, Hitchin Hill Path, the Hitchin Railway and Ransom's Recreation Ground, and the villages of Charlton, Gosmore, Ickleford and St Ippolyts. Inside a conservation area, some of the work that would go ahead without an application elsewhere needs consent, demolition is controlled, and the council judges new work on whether it keeps the character of the area. Hitchin has gone as far as giving its railway a conservation area, which tells a buyer how far the town is prepared to go on the subject of character. North Hertfordshire District Council publishes the boundaries of every one of them, and the map is the thing to check for the exact house, because the line can run between neighbouring streets.
There is one scheduled monument in the area, the strictest protection tier there is. It matters only for land that sits on or next to it.
None of this has stopped anyone. North Hertfordshire District Council received 2,580 planning applications across Hitchin between April 2024 and June 2026, 1,100 of them in the last twelve months. A town that files around a thousand applications a year is a town of people who extend, convert and add, and who are well used to doing it on paper first.
In practice, an ordinary unlisted house outside the conservation areas can usually take a modest rear extension or a loft conversion under permitted development, the national rules that let some work go ahead without a full application. Inside a conservation area those rules shrink, and on a listed building almost nothing counts as minor. The bigger the plan and the older the house, the more likely a builder's start date depends on the council's decision, so the sensible order is to find out which category the house falls into and price the extension after that.
Freedom to extend in Hitchin is on the restricted side: possible for most houses, slower and more argued-over for the older ones in the centre and the villages, which are usually the ones buyers wanted in the first place.