Despite the poor results and growing levels of frustration among supporters, Martin O’Neill was always adamant in the run-up to his departure from the Republic of Ireland job that he remained a marketable commodity in England. His point has been proven on Monday with the news of his imminent appointment by the club where he made his name as a player, Nottingham Forest.

Talks are said to be ongoing over whether Roy Keane will join him as assistant manager, but there is a growing sense that he will. O’Neill, in any case, is understood to have agreed an 18-month deal; not, on the face of it, a huge show of confidence by the club’s Greek owner, Evangelos Marinakis, but significantly longer than the average tenure of a manager in the Championship these days and roughly twice the average stint at Forest since Billy Davies’s first spell in charge ended after 2½ years back in 2011.

Aitor Karanka, who left last week, survived just over a year before departing under a cloud of fractured relations with some of the squad. The Spaniard is understood to have been told in October, at a meeting with the owner and his players, that he was expected to achieve promotion this season, as he had done at Middlesbrough before. Instead, just one win in the club’s last seven league games has left Forest in ninth place, four points off the play-off places and 12 adrift of second spot.

Martin O’Neill during his time in charge of Sunderland, in 2013. Photograph: Clive Brunskill/Getty Images

This is not the first time Forest have sought to recruit O’Neill, but while his and Keane’s particular appeal to the club’s supporters is bound to make it a popular appointment, the 66-year-old scarcely looks the sure thing he once did. He has not worked in club management since early 2013, when he was sacked by Sunderland, and it has been more than 20 years since he has faced the challenge of getting a side into the top flight.

He managed it back then with Leicester, however, and went on to enjoy good spells at Celtic and Aston Villa.

Blown away

Marinakis was apparently “blown away” by O’Neill’s enthusiasm for the challenge, and while the latter would surely have preferred a return to the Premier League, generating the sort of improvement required to take Forest up would certainly go a long way towards justifying his enduring self-belief.

It is hard to argue with some of his achievements during the initial part of his time in charge of Ireland. And his suggestion that the team’s subsequent failure to qualify for the World Cup was down to a lack of real quality was not controversial. Still, the manner of the play-off defeat by Denmark damaged him and he ultimately could not survive a run of 11 games – with just one win – over the course of a year in which Ireland increasingly struggled to pose any attacking threat.

His management style came under increasing scrutiny during that time, and after his departure he was reported to have phoned Matt Doherty to complain after the Wolves player repeated the claim made by others that sometimes the players didn’t completely know their roles.

There was always a slight question mark about O’Neill’s attachment to Keane, whose own career in England also started in impressive fashion at Forest. The Cork man’s sometimes abrasive approach with players was highlighted when Harry Arter decided to exclude himself from the squad after having been subjected to crude verbal abuse by the assistant manager. Keane eventually apologised to the midfielder but O’Neill did little to dismiss the accusation that his methods were outdated by essentially lamenting the fact that such behaviour had come to be regarded as unacceptable.

Attractive bonus

Keane was on about €2 million a year with Ireland, and industry insiders suggest it is reasonable to assume he would have walked away with half of that when the FAI decided in November it was time for a change. The new job seems likely to involve a substantial cut in basic pay, but there is sure to be a very attractive bonus element with Marinakis, who took over the club in May 2017 and is desperate to get it into the Premier League for the first time in 20 years.

Owner of Nottingham Forest Vangelis Marinaki. Photograph: Clive Mason/Getty Images

It is a notoriously difficult division to get out of, however, with a couple of owners always willing to spend big in order to challenge recently relegated sides, who base their attempts at a swift return on squads that often include quite a few Premier League players as well as parachute payments.

For O’Neill, much may depend on Marinakis’s willingness to make further changes to a squad that Karanka did a lot to reshape, the Spaniard adding 10 players upon arrival in January 2017 and then another 14 in the summer.

The Irish man will have got a strong sense of the scale of the challenge at the weekend, when he watched Forest lose 2-0 to strugglers Reading, although they did beat league leaders Leeds 4-2 a couple of weeks ago, with Irish striker Daryl Murphy playing a big part in the win. Confirmation of his appointment is expected over the next 24 hours, and his first game in charge will be against Bristol City this weekend.