The pilot intended to conduct a short flight using Night VMC procedures. Shortly after take off from runway 29C, when the aircraft had reached a height of about 250 feet above the ground, the engine commenced to run roughly, with an associated loss of power. The pilot applied carburettor heat, but was unable to regain climbing power. A skidding left turn was carried out to position the aircraft for a downwind landing on the aerodrome. Touchdown occurred on a north-easterly heading near the eastern end of runway 29 on an unlit area. The aircraft bounced and power was applied to effect recovery. During the recovery the aircraft passed over a series of hangars before stalling at a low height and landing heavily on a sealed taxiway. An inspection of the engine revealed that the power loss was caused by a mechanical failure of the right magneto which affected the ignition timing.