circuit breaker tripping

[mapj1]

That large trip sounds very like an RCD, or an older voltage operated ELCB - if predating about 1970 it will be the V/O type - no longer approved as they do not offer protection against faults to true earth, only to the wiring earth - so in practice won't save you if you drop something in the sink, or cut the lawnmower cable outdoors for example. That needs checking,and possibly replacing as a matter of concern - can you post a picture?
Also is the supply earthing scheme TT or TNC or TNS - see reference pages if you are not sure what to look for.

 

[brightspark13]

I admit defeat! I finally ended up disconnecting all 15 sockets in the ring and still couldn't get the Circuit breaker to stay up. Along the way I found 4 sockets with earths in place but not connected properly (2 of which were in back boxes without earth posts). I had the front off the fuse board which looks fine (no burns or spiders) The 2 x 30 mains circuits look to be ring type as there a 2 x live wires coming from each and have decided to call in an electrician and hang the cost. My wife is ready to move house!

Thanks to all for your help - I know where to come next time

 

[mapj1]

Hmm. There must be some more wiring on that circuit other than tht you have already disconnected. Is it possibe to see all the wiring under the floor or in the roof voids - perhaps something has chewwed into it. It sounds like it might be easier to bypass the defective section altogther and chop it out if the fault cannot be found.