Yes, you can extend in Pirbright, as long as the planners agree. The area has more than a hundred listed buildings. Five conservation areas overlap it. The neighbours send in planning applications almost every day. You can extend here, but you'll need permission first.
There are 106 listed buildings in the area. None is Grade I, 3 are Grade II* and 103 are Grade II. Grade II is the lowest grade, but it still protects the whole building, inside and out, not just the front a passer-by sees. Most alterations to a listed home need listed building consent on top of any planning permission, and that includes the changes an owner would call obvious improvements. Buyers who fall for an old building because of its character need to accept that the building's history now limits what they can do to it.
Five conservation areas fall within the area: Pirbright itself, Bisley Camp, Brookwood Cemetery, Basingstoke Canal North and Wood Street. A conservation area doesn't stop you altering an ordinary house, but it can narrow the works you're allowed without asking and make the council pay closer attention to anything visible from the street. Before you draw up plans, check whether the address sits inside one.
There is one scheduled monument in the area, the strictest protection there is. It only matters if your land is near it.
The planning register shows how much people here build. There were 2,847 applications between April 2024 and June 2026, and 1,197 in the most recent twelve months. That tells you nothing about how many were approved, only that the process is busy and routine. Plenty of people get through it. The ones who struggle are those who assumed a big garden meant they didn't need to apply.
The ground needs attention too. On the British Geological Survey's published shrink-swell classification, the worst class in the area is class 3, reached by about 21% of postcodes. That is a hazard class from the survey, not this page's own rating. Shrink-swell clay swells when wet and shrinks when dry. On an affected plot, an extension may need deeper foundations and a structural engineer's view before building starts. That's a cost to budget for, not a reason to panic, and it's cheaper than fixing cracks after the extension is built.
In practice, an unlisted house outside a conservation area may be able to use permitted development rights for modest work. A listed house, or one inside a conservation area, will need formal consent for much more. Find out which applies to the address before you exchange, not after the builder has been booked.
Your freedom to extend is limited in Pirbright. A lot of the housing is listed or inside a conservation area, so plan for formal consent from the start.