Considering the 1978 Erin in the same way as the 1984 Welsh National:
there were three "automatic" consistent horses - Mr Kildare, Beacon Light and Decent Fellow, and one "discretionary" consistent horse - Prominent King;
applying the probables rating method eliminated Decent Fellow, leaving three probables;
assessing the three to see which were also "form" horses eliminated Beacon Light, leaving two probables with form, Prominent King (6=th ranked on the ability rating) and Mr Kildare (11th). Prominent King, with the higher ability rating and the better form was the class/form horse, as implied (he didn't use the phrase "class/form horse" in the early letters) in the relevant VDW letter.
Like Righthand Man, Prominent King lacked the "ultra consistency" characteristic of what we were later shown were the main "winner in the race" profiles ("Little Owl" and "Roushayd"), but unlike Righthand Man he also lacked another characteristic, being in the top four or five of the ability rating ranking. Was he strong enough to be a bet, and if so why?
Taking Prominent King first, he was a probable with form who had shown he could be competitive at the level of the Erin (a class 90) by coming 3rd in a class 96 at the 1976 Cheltenham Festival and even more importantly 4th in the 1977 Erin, where he carried 11.11 as a 5yo in a race where weights were partly age related. Given his form run in the 1977 Erin, he clearly had a decent chance in the 1978 renewal where as a 6yo he carried 11.04, 7lb less than in 1977. In short, a well weighted horse with consistent form who had shown himself to be competitive at the class of the race.
However, on VDW's presumptions there were five better and one equally good horses in the race. Working from the highest rated downwards: Beacon Light, Meladon, Master Monday, Decent Fellow, Monksfild and Cooch Behar.
Beacon Light: In the first five of both the Life and Mail forecasts, a consistent horse and a probable, he had won at class 67 and 85 and thus could not be said to be outclassed in a class 90. He would have been a "form" horse had he won his last race but was beaten by a horse that he should have been able to beat, both on VDW's presumptions and the market's. And, as VDW commented, he had had a hard race, hard driven to win on heavy going. In the Erin he carried 4lb over his age weight for having won a hurdle of class 40 or over within the qualifying period. So a better horse than Prominent King but one whose last performance suggested he was not at peak form, and effectively penalised 4lb.
Meladon: He owed his relatively high AR to winning the Triumph Hurdle in 1977. He was in the first five of the Life's forecast but not the Mail's and was not a consistent horse nor, arguably, a "form" horse. In addition he carried 10lb over his age weight due to the Triumph Hurdle win, and was effectively penalised 10lb.
Master Monday: He was not in the first five of the Life or Mail forecast, despite having won the class 125 Irish Sweeps in 1976 and the class 89 1977 Erin for, one presumes, two main reasons. First, like Meladon, he was carrying 10lb more than his age weight, due to his win in the 1976 Irish Sweeps, and second in his last two races had run very poorly - well down the field in the 1977 Irish Sweeps and then pulled up in a minor race.
Decent Fellow: He was second favourite in both the Mail and Life forecasts, primarily one supposes due to his win in the class 117 1977 Irish Sweeps. However, although a consistent horse, on VDW's presumptions he was neither a "probable" nor a "form" horse and, like Meladon and Master Monday, was carrying 10lb over his age weight due to his Sweeps win.
Monksfield: Like Prominent King, he had not won at the class of the 1978 Erin, but had shown himself competitive by placing in classes 89 (1977 Erin), 96, 125 and 181. He was in the first five of the Mail's forecast but only 6th in the Life's, was not a consistent horse though, arguably, a "form" horse. Like Beacon Light, he carried 4lb over his age weight for winning a class 40 or above race, and like Prominent King he had been running in races of low win prize money, carrying lots of weight, prior to the Erin.
Cooch Behar: (same AR as Prominent King). Not in the first five of either the Life or Mail forecast, not a consistent horse, not a "form" horse, had never shown himself competitive at the class of the Erin. No chance.
Apart from Cooch Behar, who had the same ability rating as him and who could be discounted, Prominent King faced five better (on VDW's presumptions) rivals, three of whom (Meladon, Master Monday and Decent Fellow) had won at or above the class of the Erin. None of the five was a "form" horse, and all carried weight over and above their age weight for the race (unlike Prominent King). So apart from the ordinary risk there were five horses in the race any one of whom, if he returned to form, could be a threat. I'd be cautious about backing such a horse in a contemporary race, and it is far from certain that VDW backed Prominent King in the Erin. But he was certainly plausible, in terms both of his "form" status and his ability to be competitive at the class of the Erin. And with horses which lack the full "Little Owl" or "Roushayd" profile, this latter is a characteristic I currently see as a plus when contemplating one of the less rock-solid "winner in the race" class/form horses.
Looking at the later season runs of the five "potential threat" horses:
Beacon Light: he ran four more times after the Erin, and although always running quite well was unable to win again even when dropped a long way in class.
Meladon: only one further run recorded in the British Form Book, when he ran down the field in the Chmapion Hurdle.
Master Monday: three more runs recorded in the British Form Book, with a pattern similar to Beacon Light's.
Decent Fellow: ran four more times, showing nothing.
Monksfield: he came 3rd to Prominent King in the Erin, beaten 3.5l giving 4lb. That run showed improvement from his three previous runs, in each of which he had been giving lots of weight away. He went on to win the 1978 Champion Hurdle, then a class 73, before coming a close second, giving the winner two stone, in a class 201 handicap hurdle.
As with the 1984 Welsh National with Androma vis-a-vis Righthand Man, Monksfield's performances suggest he was indeed a genuine threat to Prominent King and shows the additional issue with class/form horses having rivals in the field with higher ability ratings. In both cases the class/form horses concerned won, and were presumably presented by VDW for precisely that reason. Both could reasonably be described as decent propositions, but were clearly much more speculative than the "Little Owls" and "Roushayds" and at the moment I can't see enough in their profiles to suggest to me that, by backing them, one would achieve an 80%+ strike rate. Though given their prices one could, of course, make a profit with a markedly lower strike rate than that.
