The calculation by Birmingham City Council of the number of employees whose salaries will be cut by the single status pay and grading review has always been something of a moveable feast. But the local authority's admission that it seriously over-estimated forecasts for the amount of money people will lose is deeply embarrassing.
Council number crunchers, amazingly, failed to give an accurate representation of the limited hours worked by part-time employees. The result was to magnify losses suffered by the part-timers, giving the impression that they were actually paid for a 38-hour week.
In the context of what the council was trying to prove - that relatively few people will have their wages cut by a significant amount - it was a crass error that handed the trade unions an open goal in their campaign for industrial action. The original figures, for example, suggested that two employees would lose in excess of £30,000 a year when in fact no one will be treated anywhere near so severely. Similarly, the 741 people originally estimated to lose between £5,000 and £20,000 is year is reduced to 523 people.
Some credit must go to the council for admitting its mistake, although the confession is likely to cut little ice with the unions. Deteriorating industrial relations, with a second oneday strike planned for next Tuesday, makes it certain that revised figures placing pay cuts in a better light will be dismissed as fantasy by anyone with an interest in stirring up discontent among the workforce.
It is extraordinary that officials responsible for the council's strategic communications did not pick up weeks ago the difference between full time equivalent employees, upon which the original figures were incorrectly based, and actual employees upon which the figures should have been based.
It is even stranger, given the prevalence of media headlines about workers standing to lose as much as £30,000 a year from the pay and grading review, that the council has waited until now to publish the correct figures.
Single status is a complex change programme and a difficult concept to sell to the wider public. At times the council's PR appears to have relied on damage limitation rather than concentrating on positive aspects.
Whichever way you look at it, 48 per cent of workers are going to be better off. Isn't that something to shout about?