Are you quite sure the 'Sweetpea' at Highgrove was a Lathyrus? Knowing
Prince Charles's fondnest for wild flowers, and that he was friendly and
often advised by the late Miriam Rothschild, could your Sweetpea not be Wood
Vetch, Vicia sylvatica. Wood vetch is fully in flower at the moment here in
Northamptonshire and as a climber, grows to at least 6ft.

MD.