Interesting controversy, if you can call it that, in the letters pages where Jenny Randles is being acused of not having properly done the research or the background fact-checking to corroborate the trustworthiness of a witness (who was of a very advanced age and who might be remembering long-ago events incorrectly). The contested point relates to the English Electric Canberra and whether or not crewmen other than the pilot/copilot were able to directly observe what was happening behind the aircraft. The witness specifically referred to a rear-gunner position which never existed in any production model of the aircraft (however, the jury is out as to what field modification might have been made to a one-off aircraft designed for a unique purpose). It is possible a man in his nineties might have let his memories blur somewhat: as his role in the crew was bomb-aimer, he was in a location where for obvious reasons he could only see forwards. But several other possibilities come to mind.
In WW2, the bomb-aimer only went into the assigned bomb-aiming position for the bombing run itself. Except for those ten minutes or so, a dedicated bomb-aimer would otherwise be redundant and dead weight on a bombing trip that could take up to ten hours flying. Weight and space was at a premium. On a macro scale, so was manpower; Britain was running out of it by 1944. Minimising the number of men in the crew was vital if you were running a fleet of thousands of heavy bombers. So the bomb aimer would do other necessary jobs during the trip: perhaps man the forward gun turret - which was immediately above the bomb-aimer station, so not too far to go when moving station. He might man an auxiliary gun station; later models of Lancaster had downward-pointing guns covering the blind spot underneath the aircraft. He might assist the flight engineer, or, crucially for this argument, as some of the skills overlapped, he might assist the navigator or enen for the rest of the trip, BE the navigator.
Which leads us back to the point raised in the current FT. The Canberra was an immediately post-war design for a jet bomber and would have incorporated lots of experience and practice from WW2. And a lot of things in an aircraft industry that had turned out Britain's wartime bombers would have carried over as "standard practice", things used in wartime that might have been considered indispensible, unthinkable to discard even in a revolutionary jet bomber.
One of those, immediately post-war, might have been something called the "astrodome". This was either a clear small turret, or sometimes just a window mounted in the spine of the aircraft over the navigator station, allowing the flight navigator to make his own in-flight observations for dead reckoning or to navigate by the stars if necessary. Old habits die hard - what if early models of the Canberra, prototypes dating from 1948 and 1949, had the astrodome built in, as, well, a hangover from WW2 experience? (I haven't checked for this) The astrodome was designed pretty much for all-round vision, after all, and if Jenny's contact had been having a memory thing, or else what he said had been misheard, it could well have been conflated with "turret" - which to a layman might have been assumed to be a gun-turret... and of course it was soon realised that a lot of things from WW2 bombers were simply redundant in the 1950's for a whole new anticipated war. Like gun turrets and astrodomes... production variants in an aircraft in service until the 1970's or 1980's would have omitted these .