Medical Validity

Private Pilots are required to have a Class 2 medical.  The validity period of the medical is determined by the age of the pilot on the day of the examination.

Age at time of medical Validity period
Under 40 5 years
Over 40 but under 50 2 years
Over 50 1 year

So if you were 49 at the time of having your medical, it would be valid for 2 years.  However a medical certificate issued prior to the holders 40th birthday will not be valid after the pilots 42nd birthday.  (This change was released in December 2006.)

The definitive document (referenced below) is JAR FCL 3.105 section (a) 3 and (a) 4

References:

See http://www.caa.co.uk/default.aspx?catid=49&pagetype=90&pageid=531

JAR FCL 3: http://www.jaa.nl/publications/jars/606984.pdf (note: this was updated Dec 2006)