How much salary should be deducted from salaries when an employee strikes for a day? That was the question in this case involving teachers. Although the amounts per teacher are small, depending on the correct calculation, the overall amount being discussed, if applied to all striking teachers, would be around £300,000 per day.

Teachers are paid monthly and, although contracted to work 1265 hours per annum, during 195 scheduled days of which 190 are days when the teacher may be required to teach. They can work over 5 days per week and there are 52 weeks in a year, which is 260 days per annum, which is the figure the school used to deduct pay from teachers who were on strike - 1/260th of their salary. The teachers argued that the figure should be 1/365th of their salary because they could be required to work on any day and do "undirected time" i.e. they work on lessons, homework, etc outside of normal school hours.

Where the contract is unclear, sums are worked out under the Apportionment Act 1870. Both sides in this case accepted that pay accrued daily - they simply argued over what a day's pay should be.

The judgement has a lengthy explanation of case law development over the years and whether the Act applies to salaries - which it is now accepted it does, although current pay structures and employment relationships were not envisaged in 1870. The Court of Appeal came down on the side of the school and said the figure ought to be 1/260th, although it also commented that the pay referable to a strike day is more logically 1/195 of the annual salary.

However, the school did not argue for that figure and, given the undirected time spent in teaching, "...relating the work to the total number of annual working days, including days which are paid holidays, provides a sensible and acceptable principle which possibly errs in the employee's favour." http://bit.ly/1PQoFOw