According to a fellow LAC who was billeted with Agnani, he'd said something about his plan to steal an aircraft earlier in the day, but no one took it seriously. By all accounts Agnani was a loner who did not socialise with his peers, and his death was 'regarded with some indifference'. Seems unlikely he'd have had help with the trolley acc, therefore. As you say, Pom Pax, nobody paid much attention to the start-up, most assuming it was an air test prior to the start of night flying, but according to the LAC quoted above, someone said 'I bet that's Nick' when they saw the Varsity making uncertain and over-corrected progress to the threshold.