I have just been reading RAF museum seminar on the Canberra. It includes mention of monitoring flights undertaken by RAF Canberras based in Australia and Whenuapai. I was not aware of this bit of history.
The New Zealanders were practising straight-in attacks at 250 feet. When it was pointed out that their bombs would almost certainly skip and go off underneath them, they countered that this would not be the case if the bombs were retarded. This was true but, although retarded tail units were just beginning to become available, there were none in the Far East. Unperturbed, the Kiwis wanted to be ready for when they did arrive and anyway, they said it was ‘more fun that way.’
Not Whenuapai but Nadi, there was a TEAL crew on stopover who observed the Valiant land and taxi to the site of the old terminal. They vaulted the fence and introduced themselves as ex RNZAF to the RAF crew who were refuelling. The RAF crew did admit they'd been atmospheric sampling and surprisingly allowed the TEAL crew to enter the aircraft but first covering a large circular instrument on the copilot's panel. OK off thread, again the date uncertain but later than the British tests at Christmas Island.