''Of course," said Andrew Roberts, "I am not for a moment trying to compare one of Britain's most admired entrepreneurs with one of history's most evil dictators." The BBC's lawyers must have been pleased to hear this, or perhaps they inserted the words themselves. Just for a moment there on Secrets of Leadership (BBC2, Fridays, 9pm), it did seem as if the fogey historian was drawing a parallel between Richard Branson and Adolf Hitler.

In any case, it was only a sartorial comparison. You probably think that the Devil has all the best tunes and the Nazis had all the best tunics. Well, while this was certainly true for most of the strutting peacocks who surrounded the Fuhrer, it was not, Roberts pointed out, true for the Fuhrer himself. His own uniform was plain and sported only a single ordinary soldier's medal from the Great War. The symbolic point that Hitler was making was twofold: he was an ordinary guy at heart, and, paradoxically, he was so far elevated above anyone else that the usual sartorial rules did not apply. So also, you see, Richard Branson, in his open-neck shirts and pullovers, is one of us and also a super-entrepreneur unfettered by the suits that encase conventional chief executives.

Half history lesson, half the most gripping seminar on management theory you'll ever hear (admittedly that's not the greatest-sounding praise), Roberts, in the first of a four-part series, managed to do what seemed unlikely: he found something new to say about Hitler. In fact, he found plenty and this was because, although for decency's sake he was obliged to scatter a few "evils" about the script, he was not interested in telling us the old, old story about what a mad and bad old Hitler he was, but in tracing his record and influence as an administrator. My bet would have been on his being a rather good one, a Gareth rather than a David Brent. But, satisfactorily, it turned out that Hitler ended up a pretty lousy man-manager, too.

He started with such promise. Hitler pioneered the modern management technique of "empowerment" or, as he called it, mission command. In other words, he devolved power and responsibility to his commanders on the ground, leaving high command to set only the objectives. This raised troop morale and was true to the fascistic celebration of the common man. It also enabled decisions to be made quickly. According to Roberts, coupled with the French determination to refight the last trench war, it accounted for the fall of France. It was so successful, Roberts claimed in one of the wicked historical ironies he pretended not to enjoy, that it was successfully adopted by Israel to wage the Six-Day War. So much for the caricature, then, of the German soldier as a slavish automaton.

Why, then, did Hitler lose? Again, you and I might think it was because he opened a second front against Russia and that the American-backed reinvasion of Europe was irresistible. Not so, said Roberts. Hitler lost because he abandoned the very management techniques that he had pioneered. By the time of the Russian campaign, he had lost faith in his generals, specifically in their ruthlessness, sacked them one by one and taken command himself. Similarly, on D-Day, the Panzer divisions being held back from the coast were not allowed to be deployed until Hitler had roused himself from his Bavarian stupor and approved their deployment. He had moved from being a visionary-style leader to micro-manager.

The failing Hitler could therefore be compared to Robert Maxwell, frantically sacking and meddling. The effective Hitler was likened to Ronald Reagan, who was not a details man either and would no doubt have agreed with the German's pronouncement that, "for a man of great ideas, two days of concentrated work is more than enough".

Only occasionally did Roberts make you wince. "I think there's a link between watching escapist films and a leader adopting a hats-off stance." That looked like an excuse to show a clip from Bedtime for Bonzo again. But, on the whole, this was a well-argued, busy 50 minutes that left you knowing more.

The first part of Brook Lapping's Maggie: the first lady (ITV1, Thursdays, 9pm), in contrast, told us nothing very new, although it was assiduous in rooting out old clips and old friends of old Thatcher. The focus of the first programme, "Her father's daughter", was Alderman Roberts. But it did not answer the real mystery, which was why Margaret adored him so. The grim teetotal bacon-slicer condemned her to four sessions of chapel every Sunday, banned alcohol from the house and 20 years later moaned about her wedding service being "halfway to Rome". "There was not a lot of sparkle in my life," she said in a TV interview in the early Seventies. Also she had reacted "rather strongly against" all the chapel-going. I'd like to know the state of her faith today, as well as of her drinking. My bet is that it was Denis, the man who put the sparkle into her life and the whisky into her glass, who was the really important influence. As for Thatcher's fall - well, there does seem something slightly familiar in the way she went about culling her cabinets and imposing her own policy formulas. Not that I am comparing for one moment one of Britain's most admired prime ministers with . . .

Andrew Billen is a staff writer on the Times