I'll admit bias, here- Although I'm only a casual fan of motorcycle GP racing, after stumbling across Martin's YT channel, which lead me to his British TV work, I find him one of the most likable, genuine, sincerely humble celebs I've ever come across.
Martin rarely talks much about himself, unprompted. But ask him about his v12, supercharged Rolls Royce Merlin static engine (so, then engine from a Spitfire, and many other WW2 planes- But not MOUNTED in a plane; It's just on an engine-stand in his barn, where it doesn't do any work- He just runs it coz it's utterly goddam glorious), and you can see Guy's eyes light up with genuine passion, talking excitedly about the minutia of the Merlin's engineering- How they managed induction that can give consistent air/fuel ratio rightside-up, upside-down, in a zero-G dive, or barrel roll. How they designed the oil system, so it'd stay sealed idling hot on a tropical runway, or far below freezing, at 40,000ft altitude.
Martin's sincere enthusiasm for the history, and the engineering skill behind iconic machines like the Supermarine Spitfire is a thing of beauty- Especially if you're the type of person who's interested in the specific, technical aspects of the fighter-Nothing TOO dry, or in-depth, of course. But more detail than most similar docos- And Martin, like Jay Leno and perhaps James May, is one of the the few celebs, where you can see this isn't just a job, or a subject where he's trying to pretend to know/care more than he does- Although Guy doesn't try to pass himself off as some expert in ww2 single-engine fighters, you CAN see a very real love and respect for the nuts and bolts and below-the-surface guts of this glorious machine.