Had to have a liner done recently for multi fuel.
our property is late victorian though have run it without problem since installation for almost 10 years.
but chimney developed a leak mortar or ” feathers” as they are known had deteriorated,
Causing smoke to leak in to loft area.
Hence liner was only option. Cost me £700. For sweeping chimney installation of liner
with adaptors and smoke cowl on chimney pot. Whith a reputable installer.
i did have quotes of over a grand though.
so pays to shop around if worse case scenario.