Perseverer, thank you so much for taking the trouble to respond to my irritated rant. Being more than a little pedantic, I was concerned - even at the time of writing - that I might have missed something, but your brief opaque nudge was all it took (within seconds) to point me in the direction where my perceived complaint of ambiguity could be resolved. I don't do The Listener regularly but, whenever I have tackled it, I have always trusted the setter's integrity of instruction. Am now kicking myself for for having been too literal or, perhaps, not literal enough. As they say, "There's no heavier burden than a great potential". Thank you again.