Henry IV Part 1/Henry IV Part 2

Shakespeare's 'Henry IV' plays are as great in girth and as complex in construction as their most famous character, Sir John Falstaff - and as witty, too, although if ever a drama exposed the dangers of verbal seduction, this is it.

Ostensibly, this is a story of civil rebellion, but one more preoccupied with other forms of loyalty, particularly drunken, juvenile Falstaff's fidelity to his own interests and to his accomplice Prince Hal. It is not battlefield deaths nor court betrayals that give these works their emotional kick, but Hal's journey from Falstaff towards filial responsibility, culminating in a personal rebellion that is entirely uncivil.

Yet Hal's inconsistency is easier to comprehend than the sturdy immutability of Falstaff. We still expect our politicians to be sly, and this seemingly wastrel prince is self- consciously taking a boozy course in spin. Noone knew better than Shakespeare the utility of persuading people in language they can understand. He contrasts flexible Hal with Harry Hotspur, the firebrand rebel who speaks only the language of war, and doesn't often shut up, either: Sam Crane plays him breathless, thrusting each sentence after the next to give opponents no time to parry. This was no way to endure in medieval England; it's no way to endure now.

By the time Hal, portrayed with marvellous lightness by Jamie Parker, becomes Henry V, he'll have added fluent tavern speak to the court diction he grew up with - plus, naturally, the language of war. He will bleed his teacher, Falstaff, white in the learning - Falstaff, who makes us roar with laughter yet is, like all great comic creations, a deeply tragic figure. Roger Allam is superb, commanding the difficult Globe stage with such shambolic majesty that he has only to raise an eyebrow to convulse the audience. But while director Dominic Dromgoole may be sensible to play for laughs, especially with the first, lighter, work, what is lost in the merriment is the nuance of the wonderful words, and the sense of Falstaff as a kind of anti-politician: a man of extraordinary linguistic dexterity but absolutely no adaptability in the sorry process of talking himself into obsolescence.

In Part Two, this emphasis on fun becomes more problematic as the chatter grows less inconsequential: Falstaff beguiles his tavern hostess almost into bankruptcy and his old chum Justice Shallow out of £1000, while Hal's brother John talks (some would say cheats) a rebel army into submission. In Allam's mouth, Falstaff's words resemble the sherry he praises so roundly: delicious, inebriating, and potentially toxic, but other characters' pronouncements are often akin to the 'thin potations' Falstaff scorns: too weak to cause much damage. William Gaunt is hilarious as doddering Shallow, but Oliver Cotton's Henry IV fades on the long speeches while others seem barely there at all. Ultimately, this cheerfully bawdy production lacks the stamina to travel from witty misrule to misery; just as Falstaff sweet-talks us into contemplating his lying and swindling with affectionate amusement, so Dromgoole deftly distracts us from the horrible culmination of all this verbosity. Hal's final, barefaced lie to his former friend, which, like Peter's denial of Jesus, should devastate, no matter what you think of the protagonists.