Following a neighbour's rat find I've figured I should do something
about fitting an air brick he

http://patchoulian.googlepages.com/airbrick

I intend to fit the 17.5" x 7.5" plate sold he

http://www.castironairbricks.co.uk/products.htm

Although the wall is about 2 foot thick I have got reasonable access to
the other side via the cellar. Couple of questions:

While the house is listed, I'm not fanatical about preserving something
as inconspicuous as an air brick - I chose this because it fits and it
looks better than a traditional brick-with-holes. It is quite expensive
though - about £50 delivered. Any alternative sources for something similar?

I can't figure out a 'work flow' for installing it. As it is the vent
will have to sit below ground level - well, it won't have to but I want
to maximise the ventilation. A bed of stiff mix (just one of those
little bags of cement/sand?), plonk it on flush to the external wall,
but I can't see how to 'render' around the 1-2" gap - is there a
technique for doing this?

Thanks, Rob