"critical comments from the likes of Harry Boardman and Steve Mayne...."

> what it was about those criticisms that made them helpful & not undermining?

Over thirty years ago Harry told me to drop the 'folkie' voice and try to sing in something closer to my speaking voice ("Why are you putting on that bloody stupid voice to sing?" would be close to the way he phrased it). I remember Steve advising me to drop a specific verse from a song simply bcause he considered it lyrically weak - which was a surprise at the time, because I thought you had to sing all the words that were in the book! There was also regular advice on repertoire. I suppose it was relatively easy to take because (a) it was constructive in content, (b) I respected both singers, and (c) they wouldn't have bothered if they'd thought I wasn't worth the effort. Neither would ever have said anything so crass as: "Do you realise you're singing flat?", although a flat singer might not have got asked to sing at the club the following week!