Thanks all for the fantastic responses.
I'm probably being thick, but how are you arriving at a single level for English? Averaging reading & writing? Also, how to get an average fine-level for maths & English? I was thinking of going backwards from the average APS. I think whoever did this at my school last year just used some ad hoc method rather than any calculation. Or are you just using the test level?
Emm
In terms of target setting, we set some very challenging targets: 5 LP for L5; 4LP for L4a & 4b;3 LP for everyone else. Each department puts together a flight plan with the only caveat of a minimum of 2 LP from Y7-Y9 and pupils reaching their targets by KS4. Some subjects, where the central KS4 target is unrealistic, set their own targets. A recent Ofsted inspector really liked the differentiated aspect of these and teachers seem OK with them.