For anyone into military radio, Patrick kindly pointed out that these Clansman SURF units are available quite cheaply on well know auction sites currently. It is essentially a variable bandpass filter I believe, designed for using VHF manpacks together in close proximity. It is a beautiful piece of engineering if slightly radioactive!
I love the worm drive – a variable capacitor and variable inductor is driven from the tuning knob via this drive.
Looks like new inside.