It has been the worst-kept secret in football but today, after taking two weeks to draw breath, Aston Villa will officially reveal that Martin O'Neill will take over as manager with immediate effect.

It is a move that will immediately increase the team's chances of success - a 21-man first-team squad will today fly to Germany and the Netherlands for a three-match tour - and will pacify supporters who have become disillusioned with what they see as procrastination on the part of the club directors.

O'Neill, the former Nottingham Forest and Northern Ireland midfield player, has managed Leicester City and Celtic with success and, three months ago, he was a member of the shortlist of candidates to replace Sven-Goran Eriksson as the head coach of England. He barely has an enemy.

O'Neill will replace David O'Leary, the much-maligned manager, who vacated his position on July 19 after three years in charge. It is understood that O'Neill has been the preferred choice of Doug Ellis, the Villa chairman, since long before O'Leary left.

I understand that O'Neill has signed a three-year contract but there are no indications yet as to who will form his backroom staff.

O'Neill is a unique character. Aged 54, he has a brilliant man-management style and, from a tactical point of view, he is versatile and successful. He revolutionised Leicester City in the Nineties and brought success back to Celtic. He is revered in Scotland.

A qualified lawyer, O'Neill has a strong sense of his own identity and, during his playing days, was one of the few men to stand up to Brian Clough at Nottingham Forest. O'Neill is sure to be just as strong where Ellis is concerned.

This a pivotal month in the illustrious history of Villa. O'Neill's arrival comes at a time when the club is set to be taken over and at a time when the squad is lacking direction. For most of the summer, Villa resembled an aeroplane without a pilot.

It is not yet known when O'Neill will join the players on their preseason tour. Until he does, Eric Steele will take charge after Roy Aitken, the caretaker manager, pulled out for health reasons.

In some ways, the timing is perfect for O'Neill. Villa have been in decline for two years and the club is in transition. His arrival is sure to inspire enthusiasm, bringing the best out of underachieving players and uniting supporters.

O'Neill will create more excitement than most of his predecessors. O'Leary had never been tested with a tight budget. John Gregory was unproven at Premiership level. Ditto, Brian Little. Not since Ron Atkinson, who took over in 1991, have Villa supporters been this excited about a managerial appointment.

But, until a deal to sell the club is arranged, money is in short supply. O'Neill might have to work with what he has - Villa have not signed any players since the end of last season - but he is sure to make significant changes in January when the mid-season transfer window opens.

There is little doubt that this is the most significant period for Villa since Ellis became chairman in 1968. Aitken knew that and realised Villa needed a fit man to control team affairs on tour.

"It's a step too far at this stage," Aitken said last night. "It's probably best that I leave it to people who are fully fit and able to work to full capacity."

Aitken could not have known that Villa were already planning how they were going to announce O'Neill's arrival.

Aitken, aged 47, is still recovering from surgery to remove a tumour after a routine check-up earlier in the summer. Although the opera-tion was a success, he has been advised to continue his rehabilitation under the guidance of his surgeon.

"When [O'Leary] left, I was asked to take temporary charge and I came back to work earlier than I should have," Aitken added. "The chairman has been very fair and backs my decision to take a back seat for a few weeks and put my own health first."

Aitken joined Villa as O'Leary's assistant in 2003 and the club have won their three pre-season games under his stewardship, without conceding a goal. However, it is unlikely that he will form part of O'Neill's backroom staff and, to all intents and purposes, he will no longer work for Villa.

But if Aitken leaves with dignity - unlike O'Leary - this will be overshadowed by the arrival of O'Neill, whose presence will provide supporters with the boost they need and, for the time being, will deflect attention from the battle to take over this great club.