"TOSTEVIN, Osmond Cecil, Flight Sergeant (203773) - killed 10 December 1929 following collision of two Siskins, one belonging to Station Flight, Duxford and the other of No.19 (Fighter) Squadron."
A little more on this one Hugh.
Tostevin was actually one of the two pilots who comprised the Duxford Meteorological Flight at the time. The accident occurred at 10 am whilst he was making the morning ascent. The accident was reported in The Times the following day. Email me off-board if you would like a copy.
I've the ORB somewhere!