Him next door had his drains cleaned and as an aside suggested that my waste
(kitchen sink) underground pipe has collapsed.
Rubble at the inlet in his manhole and a total lack of water when the sink
tap was left on convinces me he is correct.

Anyway, sods law might apply, in that the collapse may be under the
neighbours block paving rather than my side so finally my question is:-
Can I remove pipe up to the fence and remove the blockage neighbours side
(only a 2 foot run from the fence to his manhole) and run a smaller pipe
inside the current one. If so are there large to smaller connectors etc made
for underground waste?

Many thanks

Peter