Following a local flight the pilot positioned the glider to join the circuit for a landing on the grass strip 24. The wind velocity was reported as 240 to 280 degrees at 10-15 knots with occasional gusts to 18 knots. After lining up on final approach, the pilot inadvertently raised the landing gear instead of extending the air brakes. As the approach continued it became apparent the glider would overshoot the runway. The glider was banked to the right to remain within the confines of the aerodrome. The right wing tip struck the ground and the glider ground looped.