"Dave" wrote in message
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Can someone suggest how to track the noise down - eg does deathwatch
beetle make
this pattern of sound?

A deathwatch beetle sounds like someone making short, sharp taps on a piece
of wood. It is quite loud if you are in the same room, but I'm not sure that
you would hear it clearly through a wall. They are very rare in domestic
premises, as they generally prefer oak and other hardwoods that have started
to decay a bit.

Colin Bignell