Chimney relining - install hood above fire?

[boots]

I'm looking at getting my chimney relined and was wondering what kind of hood is installed above the fire / at the end of the flue?
Its an open fire and I would be putting in a flexible steel liner.
The house is almost 80 years old and smoke is migrating into upstairs rooms etc.
There's a lot of good info on the web about the liners and how they're installed etc but nothing about how they terminate above the fire.
Does the liner just come to a finish?
If so wouldn't smoke be able to travel up between the new liner and the existing chimney, thus defeating the purpose of the liner?
Thanks for any advice,
Boots

 

[kingfo]

I think there is a concrete piece called a 'gather box' which tapers in and connects to liner. Either way the space between the liner and the rest of the chimney will and must be sealed otherwise the whole job would be pointless.