Stephen, thereby hangs a tale 'from stickleback netting on the Mexborough canal to barbel hunting on private sporting estates along the middle reaches of Wessex rivers'. As an aside it was Peter (R) who witness and photographed my fish back in 1984.
Mark, I feel in the Walker, Wheat, Stone, Day , Harrigan era (1960's early 70's), it's important to differentiate between the Royalty and the 'Middle Avon' (Winkton to Britford). I'm not sure how far up the Avon barbel had populated by the 1960's but they were certainly at Ellingham and Ibsley. There are many tales of Barbel of between 14 to 17lbs either foul hooked or caught out of season (or both), by Salmon Anglers. Peter Wheat himself, writes of using 9lbs bs mono and size 2/4 Chapman Goldstrike hooks and these should have been more than capable of handling 14lbs+ barbel. When I caught my first barbel as a boy in circa 1972, I used Goldstrike and then later Jack Hilton carp hooks but eventually settled on the heavy gauge, reversed, offset point French Au Lion D'or (this was all pre Japanese chemically etched hooks).
I again have to correct myself in an earlier post, Richard Walkers best Middle Avon Barbel was actually 12.12 (not 12.04 as I previously wrote) he also caught a 12.00 from the royalty.