On Sun, 20 May 2012 23:09:10 +0100, Lobster wrote:

The house is celebrating its 100th birthday this year as it happens.
snip
The fire certainly smokes quite badly now,

Have the windows/doors been changed windows to units with decent
seals? If so the air supply for the fire/chimney has effectively been
cut off unless some additional ventilation into that room has been
provided.

... and I think it's got worse with time, which would tie in with a flue
being clogged by un-sweepable soot.

Well I guess it depends on how much of dog leg you have. Not a
chimney expert but very few chimneys are straight up, most have dog
leg in them if only so the flue passes up the side of the fireplace
directly above them in upstairs room(s).

I wouldn't expect a flue to be built at that time that wasn't
sweepable or with a dog leg that would clog. Of course it might be
constructed so that you'd clear the dog leg from an open fire place
rather than having a stove fitted. Which sort of raises the question
of why the chimney didn't have a liner installed when the stove was
fitted.

--
Cheers
Dave.