It's an instructional flight so needs to meet the rules for such things.
To find the answer you need to read AIC 18/2007 (White 133), available here:
http://www.nats-uk.ead-it.com/aip/cu...7_W_018_en.pdf
Edited to say:
Bu&&er, that AIC has expired (despite it being listed as still current).
The one you want is ORS4 No 680, available here:
http://www.caa.co.uk/docs/33/ORS4_680.pdf
HFD