A hot day in the city has left Richard Griffiths with a powerful thirst.

No sooner has he settled down at a table in a Manhattan restaurant with his wife, Heather, than he rather grandly compares his dehydration to the Nullarbor Plain, which turns out to be an arid expanse in southern Australia.

"It's 2,000 miles wide and 1,400 miles deep and there's only one plane a day," the Tony Award winner tells his slightly stunned waitress. "Dear God. We need some fluid."

She asks if he'd like something from the bar? He would.

"May I have a large gin and tonic, please?"

No problem, she says. But first: Does he have a gin preference? Griffiths, it turns out, certainly does: "Anything excessive," he says.

"Oh, that gin again," he says happily as the waitress departs, riffing off a line from Shakespeare's "Twelfth Night": "Give me excess of it."

So begins a well lubricated and often surreal interview with one of Britain's most charming character actors, a 61-year-old who is enjoying the most a productive period in his life. It's a discussion that Griffiths litters with references to Sigmund Freud, the concept of counter-transference, Albert Einstein's theory of relativity, "Henry V" and a poem by Stevie Smith.

"Oh, by the way, I do tend to ramble with answers," he warns at one point. At another, he stops mid-sentence to apologize: "Sometimes I wonder if I'm just completely draining the sense out of everything."

His wife, a former actress he met in 1973 during a show in Northern Ireland, listens politely for much of her husband's output until she spies a mutual friend, squeezes out of a banquette and flees.

Griffiths, a stocky, avuncular figure known to stop shows when a wayward cell phone interrupts the performance, is prone to playing larger-than-life parts. Indie film buffs loved him in "Withnail & I." Highbrow theater- and movie-goers delighted in his "The History Boys." Tweens have soaked him up in the Harry Potter films as mean Muggle Uncle Vernon.

"Work is strange," he says. "It's sort of getting more significant and getting more attention. I cannot tell you why that is. I'm the oldest overnight sensation in recorded history."

Griffiths is in New York with his latest English export: the London smash hit and soon-to-be Broadway play "Equus," which reunites him with former boy wizard Daniel Radcliffe. In the Peter Shaffer play, based in part on a true story, Griffiths plays a psychiatrist ordered to help treat a troubled 17-year-old who has inexplicably blinded six horses.

"It's not a whodunit. It's a why-dunnit," says Griffiths.

Written by Shaffer more than 30 years ago, the revival had a sold-out run in London's West End last year, in no large part due to the prospect of seeing Harry Potter in the buff.

Though it's been more than a year since Griffiths performed the play, he says it hasn't grown fallow in his mind. He's been thinking about it -- in his own particular way.

"I have a process Heather is well aware of -- I call it 'cooking,' where I get very inarticulate. I can't learn lines and stuff. It would appear that I'm not doing anything about it. I can rehearse and absolutely not know the lines. Sometimes, people have panicked, thinking, 'Oh, we're all screwed now,' " he says.

"It can appear like that, I freely admit. But I'm baking this thing. Now, on stage, is when you actually take off the wrapping and reveal something."

Griffiths has been cooking for decades, racking up a credit list that includes a decade at the Royal Shakespeare Company, playing Elaine Stritch's husband in the British TV comedy "Nobody's Perfect," stage roles in "Heroes" and "Art," and parts in such films as "Gorky Park," "Gandhi," "Guarding Tess," "The Naked Gun 2.5" and a terrorist in "Superman II."

"A clairvoyant once said to me, 'You'll always be useful' " he says. That stung initially, but Griffiths has realized that a character actor becomes more useful with age. "I'm very comfortable with my awareness of myself, I'm very comfortable with my knowledge and I'm very comfortable with the way my life is going."

Griffiths was born in England's Stockton-on-Tees to parents who were both deaf and mute. Sharrock says that may have helped him mature into a formidable actor.

"The first language he learned was sign. And therefore his ability to listen to people with his eyes as well as his ears is incredible," Sharrock says. "He has a unique talent for listening."