THERE was only one Brian Clough and there will, it can be stated with absolute certainty, only ever be one Brian Clough.

Yet, for rather a long time it looked decidedly like one of Old Big ‘Ead’s former players was destined to one day attain the same sort of legendary status as a manager.

For many years, during his spells in charge of Leicester City, Celtic and Aston Villa, it appeared conceivable that Martin O’Neill could achieve a comparable greatness.

The charismatic Irishman transformed the fortunes of three very different clubs. He inspired total devotion in his players, enjoyed consistent and not insignificant success and was revered by supporters as a result.

He was frequently mentioned as a possible Manchester United manager of the future and was repeatedly touted for the England job – a position he was interviewed for unsuccessfully in 2006 - back in those heady days.

When he took over at Sunderland midway through the 2011/12 season his reputation grew further still; a struggling side’s form improved instantly and dramatically, Manchester City, Arsenal and Liverpool were all defeated and the future was promising.

But after that? Disaster. The Jedi-like hold which O’Neill had always exerted on those underneath him failed to produce the desired results, wins dried up and fans grew increasingly disgruntled. Something that had at one time been unthinkable occurred - he was sacked.

It is a fate most in his profession suffer at some stage in their careers. Carlo Ancelotti, Vincent del Bosque, Sir Alex Ferguson, Jose Mourinho and, indeed, Clough all had. His sudden demise, though, left him confused, devastated, wounded.

Despite his many accomplishments in England and Scotland, there had been recurring criticisms of O’Neill and his distinct managerial style. His sides were derided for being too predictable and the football they produced drab. He was accused of being limited tactically. His track record of bringing through young players was less than impressive.

When he was jettisoned at the Stadium of Light it seemed to confirm what many had long suspected – that a man whose strengths lay in motivating players, not on the training field, was out of touch with a sport which had moved on considerably from his day. It was suggested his time had been and gone.

It was ill-advised to write Martin O’Neill off. When his Republic of Ireland side defeated Bosnia and Herzegovina 3-1 on aggregate in the Euro 2016 play-off last week it completed a remarkable redemption and proved anyone who had the temerity to dismiss him as yesterday’s man wrong.

The 63-year-old steered Ireland to a place in France next summer while displaying an appreciation of the latest methods and a willingness to put his faith in both inexperienced and marginalised squad members ahead of those proven at international level. Stuck in a bygone era? Hardly. Scared to take a chance? Don’t you believe it.

Scotland won 1-0 against the Republic of Ireland at home at Celtic Park then drew 1-1 with them away at the Aviva Stadium in their Group D fixtures and came away from both of those encounters sensing that limited opponents who had failed to impress would pose little threat to their prospects of qualifying.

Even the Irish were far from convinced. “The Scotland game in Dublin was a definite low point,” said Ciaran O Raghallaigh, an Irish journalist who covered the Euro 2016 qualifying campaign. “A lot of people thought: ‘That’s it. We’re done’. Serious questions were asked of O’Neill then. His side lacked identity, his selections seemed odd, there wasn’t the great spirit that had been expected when he took over.”

The turnaround certainly took time. But Shay Given, Robbie Keane, Shane Long, Aiden McGeady and John O’Shea were gradually omitted and the likes of Robbie Brady, Ciaran Clark, Jeff Hendrick, Wes Hoolahan, Richard Keogh, Daryl Murphy and Darren Randolph suddenly all found themselves in favour. Those promoted to their national side grasped their opportunity.

The team which took to the field in the second leg of the play-off match against Bosnia seven days ago contained only four of the players who had started in their opening qualifier against Georgia in Tbilisi 14 months earlier.

A move away from the 4-4-2 formation which O’Neill’s predecessor Giovanni Trapatonni had stubbornly refused to deviate from to the 4-2-3-1 set-up favoured by so many managers now also proved hugely beneficial.

The Republic of Ireland’s 1-0 win over world champions Germany in Dublin in October, which ensured they finished in third place ahead of Scotland, was their first triumph over a major footballing nation since they had defeated the Netherlands at Lansdowne Road in a World Cup qualifier 14 years earlier.

That result, and the outcome of their campaign, has changed the perception of O’Neill in Ireland where has been lauded as a hero. Normal service, then, has been resumed. He is set to be offered a lucrative extension to his existing contract. The high regard he is held in among the supporters should ensure he resists the temptation to return to club management and accepts it.

He will never scale the heights that Clough did. But who could? Winning back-to-back European Cup triumphs in 1979 and 1980 with Nottingham Forest was, as he would say, absolutely extraordinary.

But the prospect of Martin O’Neill being in charge of the Republic of Ireland at Euro 2016 is an enticing one. Don’t bet against them making their presence felt among Europe’s elite with such a shrewd individual at the helm.