Emailing me directions to his flat in Earls Court, Newsnight’s Lead Presenter, Evan Davis, mentions the "fascinating cluster" of estate agents where he lives. "Fascinating" and "estate agents" appear infrequently in the same sentence, but this is classic Evan Davis.

Here is a man interested in everything – the inheritor of the intellectual curiosity of Brian Redhead, a predecessor at his previous workplace, Radio 4’s Today. To Davis, a cluster of estate agents suggests a rental property boom that is forcing other traders out of business – and a very good reason to move from the one-bedroom flat he shares with his civil partner. Interesting, all round.

A year ago, it was Davis himself, however, that was the hot property. In April 2014, after 25 years, Jeremy Paxman announced he was leaving Newsnight. In only his seventh year as a presenter on Today, Davis gave the matter little thought, assuming that PM’s Eddie Mair, who had presented during some of the darkest nights of the programme’s Savile-McAlpine crisis, would get the gig.

Then the call came from Newsnight’s still new Editor, Ian Katz, formerly a Guardian Deputy Editor. If asked, would Davis consider himself a candidate? He responded with "an 80% no".

Katz phoned back. The job was not going to Mair. "And it became clear I was the candidate." The problem was that Today did not want him to go, nor did Radio 4. In the end, with no reassurances that he would be looked after if it did not work out, Davis emailed the Director-General, Tony Hall, whom he had known from BBC News in the 1990s. He hoped to discuss his options.

"Instead, he made it very clear it was probably better for me to go, and I thought, ‘If the Director-General wants me to go, I am going to go’," recalls Davis, dressed in the shirt and suit trousers he will wear that evening on air and half-sitting, half-lying on a sofa in his top-floor apartment.

But has Evans accepted a poisoned chalice? The ratings of all TV news and current affairs shows have suffered from the plethora of 24-hour and internet news, yet Newsnight has suffered more than most.

When Evans left the programme in 2001, after a stint as its Economics Editor, a "good" figure would be over 1 million viewers. These days, 600,000 would be good.

Two things, he thinks, help to explain the slump. BBC News at Ten is now in the interpretation business, on which Newsnight once had the patent. "When you look at the slew of people you get on the Ten – Robert Peston, Nick Robinson, John Simpson – they are basically people we would all die to have on our programme."

Beyond that lies a greater challenge. The net offers not only facts but opinion, plenty of it, and cheaply. Newsnight’s brand of analysis is expensive.

One can see the attraction of Evans for BBC Two. He had hosted one of its banker shows, Dragons’ Den. He might be in his fifties, but has a modern, shaven-headed, open-necked, tight-suited look. He is funny. Most of all, he had brought to Today a new style of interviewing: inquisitive rather than inquisitorial, explorative rather than confrontational.

The BBC is very committed to Newsnight, and I don’t feel it is an endangered species yet

With Paxman going, this was exactly what Katz wanted for his Newsnight.

In an article in the FT last September, he called for a shift from the current "sullen equilibrium" between interviewers and the political class. He issued a challenge to politicians: "If you dare to be a little more candid, to come to your crease a little less padded up, to answer questions rather than avoid them, we will give you the space to explain your politics and yourself."

The previous March, Davis had given a remarkably compatible lecture in Oxford on "adversarial journalism", in which he argued that, while everyone needs to be held to account, "no one should be held to account to the point where it becomes paralysing to what they are trying to do". He would, he said, "nudge the adversarial dial down".

It was a marriage made in theoretical journalism. The question is now whether the theory was right. There is no doubt that Evans has brought a refreshing change of tone to the show, his humour candid rather than snide. On the right subject, he can be brilliant.

His interviewing of comedian-­turned-savant Russell Brand ("I am trying to take you seriously") should, perhaps, have been scrutinised by Ed Miliband before he craved an audience with him during the election. When Green Party leader Natalie Bennett suffered "brain fade" about her housing policy, Davis delivered a brilliant soliloquy on exactly what she should have said.

But the fact is that Newsnight’s ratings have not improved. Indeed, they have suffered, if only from BBC One viewers staying with an extended regional bulletin at 10:30pm and from Scottish viewers now not getting to watch the show until 11:00pm. There is not, Evans admits, any equivalent of the "Paxman bounce" on the three nights a week he presents.

"I stick by my lecture," he says. "I think the dilemma is this. If a politician is spouting to you the same old boring lines of a very partisan nature, that are somewhat mendacious, what are you meant to do?

"Are you meant to take that in the spirit of the new style of political interview and say, ‘That’s very interesting, minister’? Or do you argue about it? If you argue about it, you’re back to square one, adversarial interviews. If you don’t argue about it, you just look like a feeble interviewer.

"That is why I think the only way to make an interesting non-adversarial interview is to ask questions that are different from the ones that invite the prepared partisan answer. So my basic view of this is we should make more effort to think of interesting things to ask them."

When I ask whether Katz is a supportive editor, I note that, after a quick "yeah", he chooses to praise him rather than reply directly. "He is very – what is the word? – interventionist. He is brilliant as improving every day’s programme."

There is, he adds, no political tension between them. Davis, widely seen as to the right of the former Guardian journalist Katz, says his own views  are "all over the place". Katz, he says, is similarly open-minded.

If Katz is open-mindedly reassessing interview theory, his doubts may have been visible in Davis’s election interviews, which Katz edited. These were for prime-time BBC One, so the style was bound to be a little different. Never­theless, Davis’s 50 interruptions of Nigel Farage were not his usual style. And his approach to Nick Clegg, highlighting his mastery of foreign languages and his Dutch mother, seemed uncharacteristically ad hominem.

"I think, in the end, we asked too few interesting questions and the interesting questions sometimes came across as ad hominem," Davis says. He was proud that he asked David Cameron whether he was angry about rich tax evaders. The Miliband interview "probably worked the least well": "He shut down one or two areas of questioning very quickly and there was kind of nowhere to go."

There is an even more fundamental question being asked internally about Newsnight: what is it for? Here is Davis’s summary of the argument: "On one side, we don’t want to be just a news programme, because everyone has been doing it all day. On the other side, against that, is the view that if you are too off-piste you become missable."

I understand a Newsnight staff meeting was held by Katz after the election to thrash out exactly this dilemma, and that it left some so confused that he later sent out a memo clarifying its conclusions.

The only way to make an interesting, non-adversarial interview is to ask questions that are different from the ones that invite the prepared partisan answer

With the BBC News channel winning some 200,000 viewers for its cheap-as-chip-wrapping-paper review of the papers at 10:30pm, I wonder if Davis considers Newsnight itself endangered.

He replies that, whatever its ratings, Newsnight is a formidable generator of material for the internet. "The BBC is very committed to it, and I don’t feel it is an endangered species yet."

The evening of his Newsnight debut last September, Paxman rang him and told him to "enjoy" it. On air, Davis was quickly reminded of how much easier enjoying radio is. If he is "spontaneous", he has to tell the studio director which camera he plans to be spontaneous to. He reckons it will take him two years (as it did on Today) to find his own voice.

And, I say, when did he begin to feel comfortable about himself as a person?

"Is this about being gay?"

Only partly, I say.

"Well, look, it does get back to being gay because I think you truly feel comfortable with yourself only when you’ve told people about it, and your parents in particular."

This took him longer than two years. At Oxford, where he edited the college newspaper, he realised he was much more attracted to men than women, but was still not out. Afterwards, working in London, he had a boyfriend but the relationship was kept between them.

It was only when he went to Harvard and then had an internship in a utility company in California that he realised there was no need to lie any longer. He returned to Britain determined to tell his parents.

"I set myself a deadline: ‘I’ve got to do this by Christmas.’ And I did so on Christmas Day. That tells you that it was something that was a little difficult for me."

Did it go OK?

"It went very well. They were very nice, actually, really nice."

He outed himself more publicly in 1997 when, four years after leaving the Institute for Fiscal Studies to join BBC News, he crossed to Newsnight. Gay Times asked for an interview and he "jumped" at the chance. By declaring himself gay before he was really famous the issue was neutralised, although the occasional media jokes about his body piercings, allegedly intimate, and the soubriquet "Tinsel Tits" might be considered borderline homophobic by some (but not him, it seems).

He met his partner, Guillaume Belts, a French landscape architect, in 2002. They share their impeccably minimalist Earls Court flat and something rather grander in France to which they retreat every few weeks.

"I think people in successful, long-term relationships tend to be more fulfilled," he says.

As for moving from Earls Court, it sounds to me as if Evans is more interested intellectually in his flat’s rise in value than actually finding somewhere further out to live. Nor is there any sign that Evans is about to move from Newsnight and return to Today – although, I tell him, there is a precedent.

When Newsnight’s forerunner, Tonight, was floundering on BBC One in 1976, Today’s John Timpson was persuaded to come to the rescue and present it. Unfortunately, Timpson turned out by then to have grown a face, and hair-dos, best suited to radio. In 1978, he returned to Today and began a long stint as Brian Redhead’s other half.

Davis looks, well, interested.

"Do you know," he says. "I did not know that story. That is really, really interesting." He pauses. "Shockingly interesting."