Why are we asking this now?
Sir Alex Ferguson's Manchester United reached their second successive European Cup final on Tuesday, sweeping aside Arsenal 4-1 on aggregate. They have already won the Carling Cup and world club championship this season and are heading for their third successive Premier League title.
Under Ferguson, who took over in 1986, United have enjoyed the most successful run in the history of English football, winning 10 League titles. On the international stage United have won the European Cup twice already under Ferguson. He has also led them to the World Club Championship twice, the European Cup Winners' Cup once and the Uefa Super Cup once. Ferguson also enjoyed success with his previous club, a European Cup-winners' Cup among the trophies he won with Aberdeen.
How does that compare with other British managers?
Nobody comes close in terms of the number of trophies. However, the European Cup is the ultimate prize in club football and Ferguson still lags behind Bob Paisley's three European Cups with Liverpool in 1977, 1978 and 1981. Paisley, who also won six League titles, achieved his success at a time when you had to be your country's champion team (or the holders) to enter the European Cup, whereas today up to four teams from one country can take part.
Jock Stein was the first British manager to win the European Cup, with Celtic in 1967. Stein also won 10 Scottish League titles. One of Ferguson's predecessors at Old Trafford, Matt Busby, was the first manager to lead an English club to Europe's greatest prize, in 1968. Busby also won the League title five times.
Brian Clough lifted the European Cup twice with Nottingham Forest and led both Forest and Derby County, each of them "unfashionable" clubs, to the league title. Bill Shankly won three League titles with Liverpool but retired without a European Cup to his name.
Do any managers with foreign clubs come close?
In terms of achievements with one club, no. Miguel Munoz, Real Madrid's manager from 1960-1974, comes closest to Ferguson's achievements, having won nine League championships and two European Cups. Nereo Rocco, Arrigo Sacchi and Carlo Ancelotti all won two European Cups with Milan, Helenio Herrera did the same with Internazionale and Vicente Del Bosque and Bela Guttman won the trophy twice with Real Madrid and Benfica respectively.
Ernst Happel led Feyenoord and Hamburg to the European Cup and won league titles in four different countries. Ottmar Hitzfeld won European Cups with Borussia Dortmund and Bayern Munich.
But can you measure greatness just in terms of trophies won?
No, both circumstances and the manner in which success is achieved clearly have to be taken into account. Busby, for example, assembled one brilliant team in the 1950s only to see it destroyed in the Munich air crash, which nearly claimed his own life. He then rebuilt the side to conquer Europe in 1968.
Other managers have also had a greater impact in terms of the style of their teams. Mario Zagallo coached arguably the greatest side of all time, Brazil's 1970 World Cup winners, while the Dutchman Rinus Michels invented "total football", a fluid style based on passing and movement that revolutionised the game in the 1970s. He was named coach of the 20th century by Fifa, world football's governing body.
However, while Ferguson may not have reinvented the game, his teams have always played entertaining football in the best United traditions, based around supremely talented players like Eric Cantona, Ryan Giggs and Wayne Rooney.
Doesn't United's financial muscle put Ferguson at a huge advanatage?
United's resources and reputation undoubtedly help them to recruit the best players, particularly British talent. Rio Ferdinand cost £29m from Leeds, Rooney £20m from Everton and Owen Hargreaves £17m from Bayern Munich. The club's reputation also helps when signing juniors. A boy from the East End of London might be an unlikely recruit, but Old Trafford was the only place a young David Beckham wanted to be.
Other managers have achieved success on more limited resources, notably Clough. But Ferguson has turned many a budding young player into an international superstar (Cristiano Ronaldo cost just £7.7m from Sporting Lisbon) and has not been afraid to sign older players, like Edwin van der Sar and Laurent Blanc.
So has Ferguson set out to encourage British rather than foreign talent?
United usually have more British players in their side than their rivals. Ferguson has taken particular pride in the club's home-bred juniors. Beckham, Giggs, Paul Scholes, the Neville brothers, Wes Brown, John O'Shea and Darren Fletcher, to name just a few, all came up through the Old Trafford ranks.
How important is the manager to a team's success?
While today's leading clubs have all the advantages that money can buy, man management has been made harder by player power. With their enormous wages and greater freedom to change clubs, modern players can wield huge influence. Ferguson has managed to keep players happy despite the fact that, with such a large squad, some inevitably spend lengthy periods on the sidelines.
Ferguson insists on high standards and in his early years successfully broke a drinking culture at the club. He is very protective. He stood by Roy Keane and Eric Cantona during off-the-pitch crises and kept a young Ryan Giggs out of the spotlight. He is also not averse to creating an "us and them" atmosphere, convincing players they need to stick together. He is a past master at using the media to his advantage. Liverpool's Rafa Benitez was the latest rival to attempt unsuccessfully to wage a war of words against him.
So how has Ferguson achieved what he has?
He had a moderately successful playing career and managed East Stirling and St Mirren before going to Aberdeen. In November 1986 he replaced Ron Atkinson at United, a club which at that time seemed permanently in the shadow of Busby.
After three years with little success, the 1990 FA Cup victory proved a turning point. The league title returned to Old Trafford three seasons later for the first time in 26 years and European Cup was finally captured in 1999.
Always ready to criticise referees and to question the football authorities, Ferguson has been a formidable figure. He has no time for the cult of celebrity – which was probably why he was happy to let Beckham leave – and lets nothing get in the way of his over-riding goal: winning football matches.
How long will he go on?
Ferguson has survived upheavals off the pitch, most notably the takeover of the club by the Glazer family. At one stage he talked of retirement, but at 67 he is enjoying more success than ever. United fans will be hoping he carries on for a good few years yet. It was always said that replacing Busby was an impossible job, but who on earth could succeed Ferguson?
Can anyone challenge the United boss's supremacy?
* Give any decent manager the resources that Ferguson has had and they would be successful.
* For all his attempts at lifting the biggest prize, the European Cup, he has won it only twice.
* Ferguson has benefited from a generation of great players produced by United's youth system.
* Others might enjoy temporary success but none can match his consistency over 23 years at Old Trafford.
* No other football boss manages people as well as Ferguson, who always retains his authority.
* He wins without compromising his or United's beliefs in attacking and entertaining football.