Tom Barrett e-mails to say that at Felixstowe there was a wall type mirror similar to the one at Denge, on a piece of land adjoining the remains of an old fort and martello tower at Felixstowe on the bank of the river Orwell about 1.5 miles upstream from Landgaurd fort.
This was a great area for us schoolboys and we were very intrigued when the construction began around 1934. I suspect that it had a very short life as I seem to remember that it had been removed at the time WW2. The area is now completly covered by the Felixstowe container port.
Anyone else know of this?