Out of the top 30 or so Doctor Who directors, these are the top 20, based on alphabetical order based on first name. This data isn't based on which directors have done the most episodes.
Alan W. - 7
Andrew Morgan- 8
Barry Letts- 24
Christ Clough- 15
Christopher Barry- 42
David Maloney- 45
Derek Martinus- 21
Douglas Camfield- 21
Euros Lyn- 13
Fiona Cumming- 16
Gerald Blake- 12
Gerry Mill- 6
George S.F.- 8
Graeme Harper- 18
Henric Hirsch- 6
Hugh David- 10
James Strong- 7
John Crockett- 7
John Gorrie- 6
Julia Smith- 8
