Eddie Barnes: Resignation is a hammer-blow for Scottish Labour so close to a general election

The most immediate impact will be felt in Glasgow, where Purcell has been council leader for five years. As recently as last week, he was telling friends he was determined to stay on as leader until at least 2014 so he could represent the city at the Commonwealth Games, but that honour will now pass to somebody else. Purcell's greatest strength – as symbolised by the successful Games bid – was to sell the city as somewhere open for business. The city's huge social problems remain, but it was Purcell's achievement to tell a different story.

The council now faces the challenge of budget cutbacks without a leader at the helm. Purcell, a former bank clerk and fan of Tony Blair, made much of his tough stance on public service reform (he kept a cricket bat in his office which, he joked, was to be used on his officials). But sources were insistent yesterday that the process of change which emerged during Purcell's tenure – such as the farming out of services to arms-length bodies – would carry on. As for the Games, a report this week is expected to show they are on track. The council will not grind to a halt just because the front man has gone.

In fact, it is outside Glasgow that Purcell's departure will be most keenly felt. Untainted by the sense of decline within Labour at both Holyrood and Westminster, and equipped with obvious political acumen, Purcell was seen as the coming thing.

An adept networker, he had built up a growing contacts book, ensuring he could count on the allegiance of powerful party figures such as Willie Haughey, its most influential donor, and key figures outside politics, such as Sir Tom Hunter.

Purcell was also a vital player in the party's forthcoming election campaign. He and Scottish Secretary Jim Murphy, another close friend, were known to be speaking regularly about tactics and strategy. Consequently, he had built himself up into a key player in the party's future direction. He had scotched talk of a move either to Holyrood or Westminster before 2014, but such was his growing power base that, had he announced he was opting to go to Holyrood, he would have been immediately considered as a leadership rival to Iain Gray.

All that is now conjecture. And quite whether Purcell can return from this sudden and largely unexplained crisis is not at all certain. Just a few weeks before a general election, the last thing Labour needed was to lose one of its most talented leaders.