Thank you very much for your article regarding the Kent sound mirrors (NCE 19 February). Even though I am not an engineer, I have always founds relics of wartime technology fascinating.
I have read of an underground village built in the West Country during wartime.
This included accommodation, streets and shops with shopfronts to house VIPs in the case of a German invasion, but can any readers suggest other relics that still survive?
James Wilmot, Abatec Staff Consultants, james. email@example.com