Christian McArdle wrote:
You might find something smaller, cheaper and electronic if you look hard
enough. However, they will only work if you do have a neutral, which may
require rewiring.

Thanks. As it happens, this is a new build extension. When I remove the
switch, there is in fact a blue wire in there, but not concected to
anything. Can I assume this is neutral? Does this therefore open up
the possibilities of what I can use?