Of course the other question is what was it for?
It was very much an old fashioned piece of kit. Of course its main use on Nimrod was for SAR but the Vs?
In war the codes included a set of colours of the day. These were NATO-wide colour recognition signals for aircraft, ships, and submarines.
Now submarines one can understand, and ships to some extent too, but one wondered about such distinctive aircraft as the Vs. I suppose at night, during recovery, radio comms out, an interceptor might have been sent for a VID and the bomber could fire off the appropriate colours.
Remember too that much of the design work preceded our nuclear capability and even when we were so equipped the number of devices in the world was still limited in number until into the 60s.