Inflight compass swing.
Not quite a full swing but in the 60s I was climbing through solid cloud at night in a JP when the aircraft was hit by lightning. No nasty reaction except both the gyro G4 and the E2 were clearly unreliable.
Continued up above cloud and called for advice. Nothing practical as all suggestions required sight of known landmarks. Then realised that the stars might provide an answer. Identified the north star (polaris), pointed the JP at it, set DG (Directional gyro option) on the G4 and synched the compass to 360.
Thought I was being a real Smart A*** - worked OK for the subsequent QGH on the dials. On the ground my smug attitude was rapidly deflated when the Flt Cdr asked why I had not added extra 7 degrees to the compass setting to allow for the then variation.
How are the mighty .....