Named after Hatfield House in Hertfordshire, the seat of the Marques of Salisbury.  It has small (up to 12cm) perfectly rounded flower heads of a deep pink-rose or purple-blue on acid soil.  It originated as a branch sport of ‘Westphalen’  Grows to 1.2m

Gardens found in 28 pre 2000 surveys DA  LHS WIN TR WS RW ABG ABJ WAA MS

Gardens UK 2010: DA LHS WS ESVNANAW

UK  Plant Finder: Last listed in 2005