Airvents installed “back in the day” were meant to vent the sewer. Even today they still play an important part in keeping the sewer pipes healthy as they allow the safe release of gases that otherwise would build up and up, and combine to form harmful gases that can attack and destroy the pipes.
In terms of ownership, it comes down to where the pipe in. If the pipe falls within the private section of the sewer, you would be responsible. However, should it fall on the public part, then Thames Water would be responsible for maintaining (and removing).
All sewers before 1937 are public sewers is they were already in place, laid by a sewerage undertaker or adopted by a sewerage undertaker.
In 2011, the law changed again to transfer ownership of shared lines into public ownership.
To determine whether your vent falls within the public or private spectrum, as ownership can sometimes be complicated. Please give our team a call 0800 316 9800.