My daughter has just bought an oldish ex council house which has a small round flue under the front lounge window (outside). On the inside is one of those plastic slide open/shut vents. There is a 15mm blanked off pipe close to the inside vent, and now that I have stripped the wall paper it is apparent that there was probably a gas fire on the wall. The house now has gas fired central heating, with the boiler in the kitchen. There is also a pot bellied multi fuel stove in the lounge. As there is no longer a gas fire in the lounge, is it OK to brick up the vent?
If you can, read the instructions for the stove and find out the ventilation req for it... there is nothing to stop you from bricking up the old flue and putting a new vent (if req'd) in a more pleasing position in the same room.