Davison was (until Matt Smith) the youngest actor to play the Doctor, debuting in Castrovalva at the age of 29. After his exit in The Caves of Androzani, Davison has stayed in close touch with the show, appearing in many Big Finish audios - and in 2007, he returned alongside David Tennant to play the Fifth Doctor again in charity special Time Crash.
Most recently, Davison directed and starred in 50th anniversary parody The Five(ish) Doctors Reboot, alongside former Doctors Colin Baker, Sylvester McCoy and Paul McGann.
From everyone here at The Gallifrey Times, we'd like to wish Peter a happy birthday! We'll eat some celery in your honour.