He may be one of cinema's authentic acting legends but Robert De Niro also has a reputation for being notoriously reticent with the press.

Putting that to the test was an offer that could not be refused when he came to London to promote his latest release, The Family.

Luc Besson's crime drama finds De Niro in familiar territory, playing the former head of a notorious Mafia clan who is forced to relocate to Normandy, France, under the Witness Protection Programme. Needless to say, he finds fitting in difficult, regularly resorting to his old violent ways, and placing himself at risk from vengeful colleagues keen on exacting bloody revenge.

The film, a black comedy, reunites him with Michelle Pfeiffer and is executive produced by his long-time friend Martin Scorsese. It's based on the book by award-winning French crime author, Tonino Benacquista. So, that should provide plenty to talk about, especially as De Niro seems to be in good spirits.

He smiles as he enters the room and is happy to be addressed as 'Bob'.

We start with an easy one. Did playing Fred Blake, aka Giovanni Manzoni, require much research?

"Well, I spoke to people," he says, smiling again. "I was trying to find a believable reason why he would be in France. We didn't quite find it, although Luc [Besson] said he had spoken to people in France and it would be true, or it could be. And I still think that it could be too, but we never validated it, if you will.

"There were other people I spoke to, with whom I had some experience before with Henry Hill doing Goodfellas. I talked to him [Hill] a bit. Every time I had a question I would get word to him that I needed to talk to him and then he'd call me. But also this story is what it is - it's not about accuracy in the Witness Protection Programme. The fine details would be interesting, yes, but I think that there were a lot of details in it that were good as is. How's that for an answer?"

To be fair, more in-depth than anticipated, although the finer details of his conversations with Hill would have been fascinating.

We remain on the subject of gangsters, searching for more insight into why such roles interest him, as well as cinema-goers in general. Some of De Niro's finest performances have found him connected to the Mob, whether in Francis Ford Coppola's seminal The Godfather Part II or the aforementioned Goodfellas.

"Well, if it's written well it's fun to do and the characters are interesting, especially if I'm doing them with someone like Luc or Marty Scorsese," he replies. "We have another gangster film we're going to do but it's a very interesting one. I'm looking forward to it.

"And I guess people are fascinated by them because they're against the establishment in some way... in some ways they're not but they break the law and they break the rules. I guess there are people who can write it very well and explain it better than I can why people are fascinated by them."

Once more, De Niro has dangled a juicy carrot in the form of a reunion with Scorsese. He's excited about it too. Does he mean The Irishman?

"That's the one I'm talking about."

So, what's the state of play? "Well, we're preparing it, we have a script and we're going to... Marty has another film he's going to do before that one, so we won't be doing it for a while."

The Irishman is based upon Charles Brandt's 2004 novel I Heard You Paint Houses, which focuses on the life of Frank Sheeran, one of the few non-Italians to officially associate with The Mafia. He had alleged links to the Bufalino crime family and the murder of Jimmy Hoffa, and also claimed that the assassination of John F Kennedy was instigated by the Mafia. The picture could start filming in 2014.

The Irish connection does, however, provide opportunity to delve deeper into De Niro's own personal life given that he has previously revealed part-Irish roots. Has he been able to research them?

He looks interested, leans towards the microphone and replies: "I have been doing that. It's been hard for some reason. But I am still doing it in fact."

Any idea of what part of Ireland? "No, I'm not sure. I think the southern part of Ireland. I've been working on it a lot."

Could this eventually lead to a memoir or an autobiography like the one being penned by his character in The Family?

"I haven't really entertained it much. It takes time to do that. Once Scorsese and I were thinking of doing a book together and we might still. I don't know. But that was as far as it went."

With time running out, it's time to turn to Pfeiffer in an attempt to learn more about this acting icon. Did she have any nerves about working with him?

"He is a classic example of somebody who is iconic and who sort of effortlessly puts actors at ease the moment you meet him," she replies. "I think it's also just something that he innately does with people."

Perhaps not journalists, however. On that note, and flashing another trademark grin, De Niro gets up, waves goodbye and departs the room.

The Family opens in cinemas tomorrow.