Looks like the Techies disagree with the operators.
My money is still with DD72.
see:
http://www.avrovulcan.org.uk/andy_le...l6/navplot.htm Here the box is described as Decca Doppler 72.
and:
http://www.avrovulcan.org.uk/l_brait...back_panel.htm Again refer to Decca Doppler