HELP Required to identify this.

NEW 4th April 2009 (update 22nd Sept 2009)

This unusual microvave radio device manufactured by Ferranti Scotland.
Obtained from an ex-government source. and is in new / un-used condition.
Only taken out of it's box and plastic wrapping to take these pictures.

The waveguide size is WG16. The device appears to be an adjustable probe/gap
the knurled wheel at the bottom is marked -10 -5 0 +5 +10 although it's scale
goes from -15 to +15. Adjusting the wheel to the -15 end of the scale moves
the needle-point inside the waveguide closer to the hollow part of the probe,
to about 10 thou/0.25mm Adjusting to +15 moves the probe out to about 30 thou
or about 0.7mm. On the top of the device ia a connection terminal.

My Theory?.. part of a T/R switch for radar use? or some sort of limiter/detector?
The serial number suggests that a large number of these may have been produced.
The use of WG16 suggests that the working frequency for the unit is possibly X-Band.
If you have any ideas, you can get in touch by e-mail. tb (at) qq22.net. many thanks!