You can extend a house in Bridport, and you will be asking permission to do it. There are 491 listed buildings inside the area. Five conservation areas cover the town and the villages around it. Hundreds of applications still go in every year. The answer is not no. The answer is that somebody else gets a say, and they will take it.
Of those 491 listed buildings, 472 are grade two, 16 are grade two star and 3 are grade one. The grade two count is the one that touches ordinary housing, because that is where the terraces, the cottages and the town-centre houses sit rather than the churches and the civic set pieces. Listing covers the whole building, inside as well as out, which comes as news to anyone who assumed it was a rule about the front elevation. Swapping a window, taking out an internal wall or running a flue through a roof stops being a decision and becomes an application.
The five conservation areas cover Bridport itself, the harbour at West Bay, Bradpole, Bothenhampton and Walditch. Designation does not freeze a house, but it strips out freedoms that owners elsewhere never think about, and it pulls work such as demolition, and often trees, into the consent process. Anything visible from the street is where the attention lands.
One scheduled monument sits within the area. That is the strictest tier of protection in the whole system, and it matters chiefly if a boundary happens to run up against it, at which point the conversation is no longer with the council alone.
People do alter houses here, in volume. The planning register carries 1,480 applications across the area between April 2024 and July 2026, 559 of them in the last twelve months. That is the counterweight to the constraint story. The system is busy, and it is busy because ordinary owners keep working their way through it rather than giving up.
Two of the listed buildings in the area appear on Historic England's Heritage at Risk register. That register records condition rather than danger. A building on it is in poor repair, may attract grant support towards putting it right, and will certainly attract scrutiny if anyone proposes changing it. For somebody buying an ordinary house on the next street, it changes nothing at all.
The practical position is straightforward. Outside the conservation areas and off the listed register, permitted development rights work here as they do anywhere, and a rear extension or a loft conversion is a normal project with normal costs. Inside them, permitted development is a phrase to stop relying on. Read the listing entry and check the conservation area boundary for the exact address before you buy on the strength of what a previous owner managed, because what the neighbours got away with is not a precedent, and the officer reading your application was not there when they did it.
Freedom to alter a home is among the weaker parts of living here. The protection is most of the reason the town looks the way it does, and it is also the reason your drawings will be assessed by somebody who cares considerably more about the roofline than about your kitchen island.