I too was one of the young sprogs who were allowed to fly the mighty Hastings solo as students on the OCU...and when we were subsequently co-pilots on Squadrons.
There was never a problem in finding another soul for the right seat but sometimes there seemed to be a sudden shortage of staff Navs, Siggies and Gingerbeers when the cry went up of "Co-pilot solo!" Not that these men were of a nervous disposition, often being the be-medalled survivors of the Bomber offensive and Berlin Airlift but the thought of leaving the ground with someone with just 200 hours total in any seat was a touch daunting.
On one occasion the boss was reduced to carrying out a search of the building to find a staff engineer for the task. None were found, but on entering the engineers changing room a wisp of smoke was seen coming from one of their lockers. On opening the metal door he found one of his staff engineers crouched down inside having a nervous puff.
With a look of total resignation the man shrugged and grabbed his kit before walking out to the crew 'bus!