Just started work on new extension and have revealed this iron pipe running underground. It runs down side of house(1955 detatched bungalow) around the back, and enters rear of house in floor cavity. As you can see from the image it has a threaded plug on the end, it seems to have a tar coating, which is very brittle. The pipe measures 35mm in dia. 40mm with the coating. I can't find any info on the web, wondered if anybody might be able to help??
