[rodma]

Does it not depend where the leak is? In Scotland it's usually the client's responsibility from the meter (or Toby ) onwards, so if the connection between the Toby and your side is leaking it would be yours, anywhere upstream from there would be their responsibility. The utility or infrastructure provider normally want to witness this connection in the cases of new or altered connections prior to showing the water to be turned on.

I guess you'll find out when they visit

[Paul B]

Does anyone know if a stop cock that is leaking )which is located in my back garden) is the responsibility mine or the water company to fix? Access is via a foot deep narrow hole.

If its on your property think it's you. If its on the street think it's them.
https://www.yorkshirewater.com/leak worth checking with your local water company but suspect they will be them same.

2. Outside your property, but still on your land​

You're also responsible for the pipework from the boundary of your property up to where it enters your home.