Henry IV Parts 1 and 2, Shakespeare's Globe, London

During an opening-night downpour, Roger Allam's Falstaff suddenly segued into "Blow winds, and crack your cheeks..." The audience loved this, almost as much as they loved Doll Tearsheet vomiting over them a few minutes later (well, she has been drinking "too much canaries").

The unbuttoned, sometimes casual, style at the Globe suits these plays, all six hours of them, very well, and helps release them into a new democracy beyond the RSC. For the first time, I think, we see Mistress Quickly's husband, silently smoking and drinking in the tavern, not to mention Falstaff playing a mandolin and pissing live onstage in a pint pot.

Director Dominic Dromgoole starts the action in the foyer, with mummers and medieval knockabout, making merry with the legend of Falstaff , with a lot of "jolly rumbelow" and "summer is acumen in." The auditorium is hung with heraldic banners as the old king (moodily played by Oliver Cotton) rails against the rebels and his son and heir who's losing princely privilege with "vile participation".

It's always a joy to see these brilliantly plotted plays together: their tapestry is one of political upheaval, rustic recruitment scenes, drinking, robbery, battles and the making of a new king. Jamie Parker risks making Prince Hal a bland cipher of intent, but his low-key approach pays off with plausible, sudden venom in the rejection of Falstaff.

Falstaff, having survived the buffetings of authority and Mistress Quickly (Barbara Marten is on the warpath once her husband's disappeared in Part 2), and hired only those soldiers who don't buy back their commission, claims that all the laws of England are at his commandment.

There's never any doubt about the justice of his dismissal, especially as Roger Allam makes him such a dangerously manipulative operator. Allam speaks the role as beautifully as any actor in memory, including the late Robert Stephens. He's more knightly than Stephens, less mountainously corrupt. But he's not really all that fat, or gross; he's less a Manningtree ox than a beadier, longer-haired version of Christopher Hitchens.

But he's buoyed on a bubble of wit and clever bartering throughout, and insists on keeping the audience in on the joke. It's the kind of performance that prospers in the Globe, hogging 20 per cent of all lines across the two plays, and Allam has probably never generated as much affection in all the years of his career at the RSC and elsewhere.

Dromgoole's company of 20 actors does sterling work in the doubling department: William Gaunt is both a dignified Worcester and a hilariously whinnying Shallow, thrusting Falstaff into a gloom of nostalgia with his pitiful reminiscences in the Gloucestershire scenes; Sam Crane finds common cause with an unusually scruffy Hotspur and a swaggering Pistol; Jade Williams is a touching Lady Mortimer, with a lovely Welsh song, and a sexually abused Doll; and little Paul Rider does a lovely slow burn as Bardolph as well as an acid-tongued Scroop.

This is the Shakespeare masterpiece where diseases are turned to commodity, the hostess is eaten out of house and home, citizens are urged to construe the time to their necessities, and white hairs ill become a fool and jester. It's our national pageant, and it's suddenly, and gloriously, available in London's most informal and genuinely popular theatre.

To 3 October (020 7401 9919)