A controversial shake up of Birmingham City Council’s salary structure is in chaos after hundreds of workers won appeals against wage cuts.

More than 350 town hall staff successfully challenged a pay and grading review, under which some stood to lose more than £12,000 a year.

Of the appeals heard so far by HR officials the vast majority – 81 per cent – resulted in re-grading and a pay rise.

Most who challenged the way their pay had been worked out were told that a job evaluation point-scoring process used to arrive at a salary grading had been mistakenly applied to them when the new system was devised more than a year ago.

This meant that the value of their job, and salary, was incorrectly calculated.

Some employees, including business analysts, benefit fraud investigators and architects, had their points total increased by a third following the appeal hearings – immediately pushing them into a higher salary band.

About 4,500 appeals have been lodged, but the true figure will be higher because some are group actions by people carrying out the same job.

The council is also defending 2,400 employment tribunal unfair dismissal claims resulting from the pay and grading review.

Under the salary shake up, which was supposed to iron out inequalities between men and women and blue and white collar jobs, about 5,500 out of 40,000 council workers were told their wages would be cut. Half qualified for a wage rise, while the remainder saw no change in their pay.

Cabinet equalities and human resources member Alan Rudge, who pushed through the salary changes, insisted the appeals success rate had been expected and budgeted for.

Coun Rudge (Con Sutton Vesey) said employees in line to lose the most money were being prioritised in the appeals process.

Mistakes had occurred because hundreds of workers, acting on union advice, had refused to fill in job evaluation forms in 2007, he claimed.

This meant that accurate information upon which to award the new salary grades only emerged when the appeals were heard.

He added: “We knew this was likely to happen and we budgeted for it. There is no problem at all.”

But opposition Labour group leader Sir Albert Bore said the original grading process was “inept”.

Sir Albert (Lab Ladywood) claimed that “elite” groups of staff in high-profile units such as the chief executive’s office and the cabinet support team were being favoured with fast-track treatment.

Committee clerks, however, were still waiting after a year to discover when appeals against wage cuts of £15,000 a year would be heard.

Protests are not confined to staff in line to lose money. Almost half of those lodging an appeal did so because their salaries remained the same under the new system, when they thought they deserved a pay rise.

Sir Albert added: “This whole thing has been so badly managed.

“Faithful servants of the council, people who have worked for the city for a long time, are being let down and many are leaving to find other jobs.”