When questions are raised about P3's monitoring of the droop reaction, it must be remembered that at the time the squawk code was not given till after TO.
As I recall through the blur of 40 years there were only a few seconds between climb clearance and squawk being given and the retraction of the droop. In these seconds, P3 duties required him to write down the clearance and select the squawk.
John Collins was a Vanguard training captain and an ex-Trident pilot. I have always believed that he did in fact spot the mis-selection and made a desperate attempt to rectify matters.
The suggestion at the enquiry that he might have been larking about distracting the crew at a critical stage of flight was a deeply offensive example of the level that lawyers will sink to in attempts to avoid blame for their clients.