“The film business has changed hugely,” Jeremy Irons flutes. “You seem to spend about 30 per cent of the time producing the films and 70 per cent talking about it.”

Does he enjoy the talking bit?

It’s hard to describe the noise he makes. It’s a sigh, but one that expresses as much frustration as regret. Irons really does like to talk, but he has a habit of steering the conversation through regrettable diversions. There was that time when, in the course of a chat on gay marriage (which he ardently supports), he speculated that the enabling legislation might allow a chap to marry his son for tax purposes. “If a man puts his hand on a woman’s bottom, any woman worth her salt can deal with it,” he once pondered.

There’s more where that came from. He seems a perfectly reasonable man, but, at 67, he hasn’t yet learned to be wary with parenthetical musings.

“It can be fine. You and I can talk, but if I am in Japan, I have an interpreter. It can become mind-numbing. I was caught by the internet. I like to sling a ball about and say: ‘What do you think of that? It’s a crazy idea, isn’t it?’ But now there’s this huge octopus called the internet. You say something and people take it as gospel. I’ll think: ‘No! Wait a minute. I was just throwing a ball in the air.’ But I have realised you can’t do that now.”

Irons is very much as you might expect. Looking nimble for his years, he sports the sort of pepper-and-salt moustache that went out of fashion with Anthony Eden. Not one, but two scarves are knotted round the long, impressive neck. Although he throws fewer balls around now, he makes no attempt to hide his unreconstructed grandness.

“Now and then you meet an interviewer and you think: I just want to chew the fat. This is a great shame because . . . Oh this is wonderful French linen. I’ve got one of these. They are fantastic.”

What? Hello? In mid-sentence, he has lent forwards to examine a huge cloth draped over the circular table that separates us. So in which of his many houses (some reports say seven, others five) does he keep the posh French linen? Such a cloth would suit Kilcoe Castle, the pile he owns in Co Cork.

“In Oxfordshire. We take it out at Christmas. We don’t really use it for the rest of the year. People would just spill wine on it. They’re bed sheets actually.”

Where were we?

Since breaking through with the ITV production of Brideshead Revisited in 1981, Jeremy Irons has rarely been off the screen or away from the stage. He gave us two of cinema's great performances as twin gynaecologists in David Cronenberg's Dead Ringers in 1988. Two years later, he won an Oscar for Reversal of Fortune.

In 2016, he really is everywhere. He plays GH Hardy, the eminent Cambridge mathematician, in Matthew Brown's irresistible The Man Who Knew Infinity. He occupies the top floor in Ben Wheatley's deranged High-Rise. And, of course, there's the corporate juggernaut that is Zach Snyder's Batman v Superman: Dawn of Justice. Irons follows Michael Caine and Michael Gough into the role of Alfred, Batman's butler.

Tough butler "I thought: let's bring something new. Let's forget about the butler," he says, winding up for a lengthy muse. "I remember spending time with John-Paul Getty and looking at the people who were around him. I knew they were ex-SAS. They were very welcoming and very hospitable. They could pour a devastating dry martini. But you knew that if there was any trouble they could give you a karate chop to the neck that would wipe you. That was the sort of Alfred I tried to find."

It's been a funny sort of career. By the time he came to play Charles Ryder – initially an undergraduate – in Brideshead Revisited, he was already 31. He'd appeared in the original theatrical production of Godspell. He can be spotted standing on his head in an episode of Playaway. So, I imagine he hadn't been starving.

"Those were building years," he says. "Three years at Bristol [Old Vic Theatre School]. I came to London. I spent nine months doing domestic work and gardening because I knew I wanted to get a West End show. So, when I was offered jobs in Stoke or Leicester or whatever, I'd say no. Eventually, I got Godspell. It was gently building."

He was initially offered Sebastian Flyte, the doomed aristocrat, in Brideshead, but wisely pressed for the role of the cautious, middle-class Ryder. It is hard to explain quite how intoxicated the world became with that absurdly lush production. The deliciousness offered escape during a period of great economic uncertainty.

“I am still realising that, in a way,” he says. “I remember walking home to Hampstead and I knew it was going out. There was nobody on the street. I thought: that’s good; people are watching. I didn’t go to America to launch it because I had the flu. I heard it went well. Then I began hearing about Brideshead fashion. People were wearing tweed jackets and cutting their hair shorter. People are still watching it. I’ve never heard anybody say anything rude about it.”

He has been married to our own Sinead Cusack since 1978. Irons was drawn to Ireland and spent time communing with that great Cusack acting dynasty in and around Dublin. It was a conversation with the film producer David Puttnam – who has had a house in Skibereen for decades – that persuaded him to buy property in the Rebel County.

I wanted a bothy "I remember sitting in David's house and I said: 'I'm home, David'," Irons intones airily. "He was thrilled because he wanted friends there. So we got in his boat and he was pointing out ruins and houses for sale. I saw the tiny fisherman's cottage – actually a smokehouse – that I wanted to buy. I wanted a bothy that I could just close the shutters on for six months."

He got his bothy. Then he went on to buy Kilcoe Castle, which he restored assiduously, before stoking controversy by painting it in a warm grapefruit pink. He speaks warmly of the “indented coastline” that reminds him of the Isle of Wight where he grew up.

“Because it’s a republican area, they weren’t seduced by fame. If you were English, you had to prove yourself,” he says.

Has he managed that?

“I think I have because I did the castle. I was the biggest employer there for about three years. ‘The English knocked the top off this,’ I said. ‘I think it’s up to the English to put it back on.’ They saw that I was hands-on. I wasn’t some fancy-pants film actor. I was a builder. I became the joint master of the hunt. I sing with musicians in local bars.”

He paints a colourful picture. The former public schoolboy waving pint glasses and bellowing as last orders are called.

“They accepted me for what Jeremy was, not for some high-falutin’ film actor,” he says. “Which is what I need. Which is what I like. I do this work, but I am uncomfortable in situations where you’re hyped into something you’re not. Just because you’re in a long limo doesn’t mean anything.”

He has now talked himself into a wistful reverie.

“I feel my skin shedding as I drive west from Cork airport.”

The line is delivered as if plucked from Byron.