Continuing Professional Development and short courses

Birkbeck University of London
  Certificate in Garden History
  Diploma in Garden History
  (Various Garden History short courses and weekend events are also available)

Capel Manor College (in conjunction with Birkbeck University
  of London):
  Certificate in Garden History
  Diploma in Garden History

The University of Greenwich  PG Certificate in Garden History

University of Cambridge, Institute of Continuing Education
  Certificate in Garden History
  Advanced Diploma in Garden History 

University of Oxford, Department for Continuing Education
  English Heritage Professional Training in the Historic Environment course: Historic Gardens and Landscape: Threats and the Conservation Tool Kit.

Various Garden History Courses such as Garden Building and Design in Europe From Ancient Rome to Modernism.

English Heritage Professional Training in the Historic Environmnet course: Managing Wildlife in Historic Places'

West Dean College  3 day Master Class in Ecological Management of Historic Properties and Sites.