Pontius
I remember that 1/2 pudding basin or was it colander protective helmet being issued on trial to several nav/ bomb aimers at RAF Bruggen for use when flying with the Canberra B(I)6 Hornet Squadron.
I think the idea was to make it easier for the bomb aimer to gain access to tbe nose section of the aircraft when flying the LABS(bomb tossing/flinging) manoeuvre which I should imagine was quite violent with every chance of bashing his head/helmet in such a confined space.
Some of the guys kept their helmets after the trial for that purpose
Never ever saw one again after leaving Bruggen.