Today's surprise visitor was an RNZAF Lockheed P3K2 Orion, NZ4202.
I hadn't seen one of these in a long time. Last photograph was a P3K on the missed approach at Wellington back in December 2013. The last time I got close to one was in March 2012 at the RNZAF 75th anniversary open day/ airshow.
*MAD - Magnetic Anomaly Detector. That thing which helps detect underwater submarines, and I suppose ships in low cloud?