Hamish Marson wrote:
I have a victorian semi-detatched with an old fireplace in the
downstairs lounge (AT rear of building). We want to put a new
fireplace & gas fire in there.

Does the installation require a new flue, or is the existing chimney
able to be used for the gas fire without any alterations? The chimney
itself is in he centre of the house, and serves all 4 rooms in the
main part of the house (2 on ground floor, 2 on 1st floor) and has 4x
separate chimney pots at the top indicating 4 separate flues (One to
each room).
Almost certainly it will need a liner.
An acquaintance of mine fitted expensive gas fire when refurbishing his
ground floor Vic London flat.
The first time he lit it the flats upstairs complained of fumes coming
through the chimney breasts into their flats.
Quote to fit liner (it will need a crane) are in excess of £2k ...