4. Regulation 3 does not apply to any aircraft—
(a)equipped with serviceable secondary surveillance radar equipment which includes a pressure altitude reporting transponder operating in Mode A and Mode C; or
(b)of which the commander has obtained permission to enter any of the airspace restricted by regulation 3 from, as may be appropriate, the air traffic control unit at—
(i)London Stansted Airport,
(ii)Essex Radar, or
(iii)Farnborough Radar.