Just how far will a British gentleman go to support the man who dresses him?

Hugh Bonneville, who plays the usually very proper Lord Grantham on PBS’ “Downton Abbey,” tore off his tie and unbuttoned his shirt Saturday night before a roomful of TV critics to reveal a T-shirt that read “Free Bates.”

So, OK, it wasn’t exactly a striptease. And it’s not as if Bonneville dropped his trousers – something that’s happened, onstage, during at least a couple of Television Critics Association events in recent years – but for PBS’ portion of the group’s summer meetings, which began this weekend in Beverly Hills, it counted as a Moment.

And a nearly spontaneous one at that, Bonneville having conceived the idea only that morning. “I don’t know how it came up, but I said, ‘How about getting a T-shirt with “Free Bates” on it?’ and someone went out “and bought a T-shirt and stenciled it on,” he said afterward.

“Downton Abbey,” whose second season on “Masterpiece” last week received 16 Emmy nominations, including one for outstanding drama and another for Bonneville as a lead actor, is giving once-staid PBS plenty of moments these days, none perhaps more anticipated than the one in which Maggie Smith, as the dowager countess, comes face to face with Shirley MacLaine for the first time onscreen in Season 3.

PBS ran a teaser reel for critics and let’s just say hilarity does ensue.

Offscreen, too, apparently.

The Emmy-nominated Smith, alas, wasn’t among the cast who crossed the pond for the critics’ shindig. Besides Bonneville, they were the Emmy-nominated Brendan Coyle, who plays the unlucky Bates, currently serving a life sentence for a murder we’re all pretty sure he didn’t commit; the Emmy-nominated Michelle Dockery, who’s Lady Mary; the Emmy-nominated Joanne Froggatt, who portrays Bates’ loyal wife, Anna; and Elizabeth McGovern, who’s Cora, Lady Grantham.

And we also got MacLaine, who may have had less distance to travel but who came prepared to play.

When I asked the actress, who’s playing American Martha Levinson, Cora’s brash mother, whether she and Smith had ever met before, she started to laugh.

“Oh, God. Should I tell this story?” she said.

Of course she should, I told her.

“Well, we were lovers in another life,” she joked.

Turns out, though, that while MacLaine thought the two were meeting for the first time in this one, that wasn’t true.

Smith “told me that we had met 40 years ago backstage at the Oscars next to the catering table,” MacLaine said.

“And I was up for something, and there was this big chocolate cake on the catering table. And whatever I was up for, I lost, and somebody else won. And Maggie said, ‘You know what you did, dear? You tucked right into that chocolate cake and said, ‘F— it. I don’t care if I’m thin ever again.’ She remembered more than me, but then she’s younger than me. She’s one year younger,” said the 78-year-old actress.

“She brought that great spirit she has on to the set,” Bonneville said afterward of working with MacLaine. “When Shirley clapped eyes on [Smith], it was like Stanley meeting Livingstone. It was like these two great legends, or these two great explorers of our industry, meeting. And I think Shirley literally lifted Maggie off the ground with a hug, saying, ‘My God!’ It was great. It was a great moment.”

So, apparently, was learning about the Emmy nominations, which, unlike last year’s, aren’t in the miniseries category “Downton” won last year, but in drama series.

“We feel like the interlopers,” Bonneville said. “We come from a little strange island across the sea, and we’ve made our show, which seems to have caught fire around the world in a way we could never have anticipated,” so to be in the running with shows like “Mad Men” and “Breaking Bad” and “Homeland” “is just a real honor for us. It really is.”

Fame does come with a price, though, and Bonneville’s been paying it. “I get frisked more at airports,” he said. “I’ve had more hassles since this show’s become popular from customs agents – not wanting to give me a hard time, but they’re just more interested in seeing what’s in your bag. Yesterday, I found a pen that I’d lost. Because I had to take everything out at Heathrow, and there was the pen I’d been looking for for six months. So there’s an upside.”

Bonneville, who also stars in BBC America’s mockumentary “Twenty Twelve,” playing a bureaucrat involved in the planning of the 2012 Olympic Games in London, recently came face to face with the man whose job he’s been making fun of.

“There was a service in celebration of the Olympics in Westminster Abbey last Sunday. And a lot of the people who’ve been working on the Games in various sorts of ways were there. And I had the pleasure of meeting my real-life counterpart,” the actor said.

“In our show, I work for something called the Olympic Deliverance Commission. In real life, it’s called the Olympic Delivery Authority. And I met Dennis [Hone]. He’s a bit shorter than me,” Bonneville said. “He’d taken it all in good spirit. Sometime he had to watch through his fingers, but on the whole,” Hone seemed to get the joke.

As for the actual Olympics, which officials hope will prove a long-term economic boost to the long-neglected East End of London, where Olympic Park is located, Bonneville’s impressed.

Except, perhaps, by the humongous Anish Kapoor sculpture that’s about to become a fixture on our television screens.

“The Orbit’s not my cup of tea [but] apparently it’s art, so there you are,” he said, chuckling.