Although tench readily inhale large baits intended for carp, smaller baits that mimic their natural food can often yield more bites. Crunchy little casters are unbeatable tench tucker, as is hemp. They're also complete suckers for sweet corn, worm and maple peas but massive 25mm boilies?
I can understand why Martin didn't hair rig his bait, it was originally designed in the 70's purely for carp as it was believed years ago but so was the boilie so why he used them to catch tench instead of sticking to his usual sweet corn I do not know, unless of course it was the ingredients used in the HNV bait that singled them out?
So how would you present to a tinker tiinker, would you ever consider a large boilie?
You seem to have forgot PASTE HNV paste was used before boilies came into being and even when they were one hell of a lot of people did not know how they were produced.