Kay wrote:
We're installing a wood stove this summer, which means we want to line
the chimney first.

But I notice we have a bees nest in the chimney. Is putting a liner in
likely to disturb them?

They are going in through a tiny hole next to the mortar in the top
course of stones, about 6 inches below the chimney pots. It seems to be
one arriving or leaving every minute or so, so it doesn't seem like a
large colony. They look to be bumble bee type things, round and fluffy,
with white bums, and rather small for a bumble bee. Any thoughts?

It will certainly disturb them if they're inside the chimney. There's
a vague possibility that they are just in a cavity in the brickwork,
if it's old and not maintained. One every minute or so does mean
it's a small colony - it may increase as the season goes on. Your
best bet is unfortunately to destroy it, unless you can wait 'till
later in the year after the frosts come.