Is it permissible for a flue to discharge across a neighbouring
property? I thought it was outlawed a while back?

Next-door neighbour had a new (Vaillant combi) boiler fitted last week.
The new flue exits their side wall (which forms the boundary between our
properties) turns up to about 12 feet and has a 90deg elbow at the top
which is angled at about 35 degrees to their wall (so it's not firing
directly at my wall).

The gap between our houses is roughly a metre and forms the access to my
garden. The walls are the side walls of both our single storey 'garage
with utility behind', topped by a standard pitched roof. The terminal is
quite near their apex, but due to a difference in height between our
properties, does seem to be aimed nicely at my (uPVC) fascias.... (and
as you can imagine with the cr*p weather we've been having today, the
plume has been quite prominent).

Should I be concerned about this? To whom would I complain, CORGI?
Building Control? (and risk it becoming 'a dispute' which would need to
be disclosed at some future sale).

I know it's not DIY and I know you're not lawyers, but there are some
knowledgeable folk on here and I would welcome any comments.

In any case, it's better than the original, which fired straight out of
their wall across my utility window and back door....

--
Fred