8" sewer? - What is this pipe

[tomboy]

Hi all this is my first post so please be kind.
The property is a 1937 built house. I have a brick built manhole aprox 3 foot deep with a 4" private drain running across the width of the garden.
Running parallel to this drain is what appears to be an 8" clay pipe ecased in concrete. The top of this pipe is about 2 foot below the surface. My question is, what would this 8" pipe be?
I asked Thames water if it was their sewer but they said it wasnt on their map.
The 4" drain/manhole picks up soil and grey water from my house, the houses upstream and at least 1 house down stream.
Thanks in advance
Tomboy

[andpartington]

well it cant be for your waste because it is above the bottom of the man hole my guess would be a street grid pipe or it could contain services elecky or water
A picture might help
Is the pipe near the street front or back garden

[lutonlagerlout]

sounds like the main sewer run
especially if its enclosed in concrete
the 4" pipe will be yours and the larger 1 the whole streets
IMHO
LLL

[tomboy]

Thanks for the replys. The pipe is in the back garden i'll see if i can work out how to upload a picture.
Thanks
Tomboy

[Tony McC]

Could be an old culverted spring.