Grad School
Colin Baker has a PhD in haberdashing.
Paul McGann got his degree in squid wrangling
Matt Smith has an advanced degree in tiny particle mechanics.
Peter Davison wrote his thesis on spacetime continuum travel.
Tom Baker studied basket weaving (above water).
Sylvester McCoy is a doctor of pepper pickling.
Patrick Troughton studied floor tile patterns in Renaissance art.
Jon Pertwee has a PhD in tea tasting.
David Tennant has a doctorate in hitchhiking.
William Hartnell studied European cartography.
Christopher Eccleston is an expert in zero point module design.