eden wrote:
Thanks for comments so far....

photos posted on flickr

http://www.flickr.com/photos/35218568@N03/

Have had a further dig and the green wire is connected to a metal
spike thing in the earth. Surely the cable will weather if exposed
like this??

Does the covering look like Hessian on the brown cables? It looks like
Poly Butyl Jute (PBJ) cable and will probably be end of life. Do not
tamper with it but call the local electricity supplier (the old
electricity board for the area) and state that you may have a PBJ supply
cable and you would like it checked. If they do replace it it will be
for free.