The devil, as always, is in the detail. Only 15.8 hours were spent teaching their own lessons.
So how do they spend the rest of their time? Well, there is lesson preparation and assessment, pastoral care and discipline, coaching sports and directing school dramas.
Then there is (and we are sure these are on the list of 25 tasks banned by the workforce agreement) record-keeping, photocopying, displaying pupils' work and other administrative duties, adding up to two hours a week.
And the last hour of their working week? Er, filling in the diary for the review body.