David Angus of the Seaham online community history project www.east-durham.co.uk has tracked down the probable location of the Seaham sound mirror, though cautions “it is at least 55 years since I saw it and then only once.”

He’s found two men who agree on the location shown below. Apparently the mirror may have been used for shooting practice by the local Home Guard during World War II.

Sadly it would appear it is no longer in existence; when it did exist it looked something like the surviving Sunderland mirror.