Sweet William, Little Angel, London

Michael Pennington has been bonkers about the Bard from the age of 11 when his parents dragged him to the Old Vic and he was mesmerised by Macbeth. Since then he has, by his own reckoning, spent 20,000 hours on stage performing Shakespeare, to say nothing of the hours devoted to reading and rehearsing the works. This accumulated experience is distilled now in Sweet William, a wonderfully perceptive one-man show that interweaves biography, autobiography, performance, cultural commentary and textual analysis.

The two hours teem with the insights of a highly intelligent practical man of the theatre on a practical man of the theatre who was a genius. For example, picking up clues from one of the Sonnets and with insider-knowledge of how performers write home, Pennington develops the theory that in his so-called "lost years" between leaving Stratford and surfacing in London, Shakespeare was a touring actor and the sort of company member who is always complaining about the script. The difference in the Bard's case is that his dreams of improving on the stuff he had to spout as a player were not self-deceiving.

Crucial to the new voice that Shakespeare brought to the drama, argues Pennington, was the ability to "lurch" between high-flown poetry and intimate human detail – "the simple, banal or off-the-point". Taking a scene in the third part of Henry VI, he suggests that Christopher Marlowe could have written York's ringing line about Queen Margaret "O, tiger's heart wrapt in a woman's hide", but that the Queen's reference to York's son Richard as "Dicky, your boy, that with his grumbling voice/ Was wont to cheer his dad in mutinies" adds a note of (here insolent) domestic intimacy to her jeering that is characteristically Shakespearean.

Pennington notes that contemporary writers, such as Robert Greene, were piqued that Shakespeare collapsed the class distinction between vulgar actor and genteel author. Likewise, professional commentators on Shakespeare may now feel a twinge of envy that Pennington has the edge on them by being able to illustrate his perceptions with such deft, lucid performances. You emerge from this graceful show with your sense of Shakespeare refreshed and augmented.

Touring, including 11-13 October at Minerva Theatre, Chichester (01243 781 312)