I have a Magiglo Gas fire with an open bed of "coals" under a pre-cast flue
formed in the inner blocks of the cavity wall.
A recent post made me realise that it is very innefficient and I also get a
cold draught from the chimney whith certain conditions.

What are the options? I recall reading that I cannot fit a balanced flue
through a cavity wall (although where the fire is fitted there is only the
outer leaf of bricks behind the fire.

We don't really like fires behind glass - but this might be a dated
prejudice.

Any suggestions for something that would be energy efficient and avoid the
draughty flue - and be complient with regulations?