On Sun, 2 Mar 2014 10:14:12 +0000 (UTC), Andrew Gabriel wrote:

What do people recommend? Should we connect our guttering
(assuming
it's possible) or keep separate? Is there a real chance of damp
due to
the gap, or is it best to keep as-is?


I formed a piece of lead to direct any water which comes
through the gap into one or other gutter.

This is the way to go, water coming down the roof does not hit the
top of the end stops or down the small (1/2 inch) gap between them.

As others have said don't share "services" with neighbours unless you
really, really, have no option. Even then such shared things ought to
be in the deeds and the procedure etc for dealing with and paying for
problems laid down.

--
Cheers
Dave.