HI
Menage, lime pit, gravel pit, pond, burialmound, herb garden?
The 1960s map does look like stables to me.
From earlier maps it looks connected to Shenley Lodge
National Archives has some on the area eg .....................
Title deeds of the High Cannons Estate, Shenley and Ridge, 1534-1912
http://www.nationalarchives.gov.uk/a2a/records.aspx?cat=046-dehcc&cid=-1#-1Deposited 12 August 1948
Creators Durant family of Shenley, Hertfordshire
Administrative history:
The nucleus of the estate, the manor of Holmes alias Cannons, belonged to the former monastic foundation of St Bartholomews, Smithfield and the collection begins with a copy of the Crown grant to John Alwey and his syndics in 1543 (DE/HCC/27433) An heiress carried High Cannons to her husband, Edward Wingate, who bought out her sisters. In 1653 he moved to Lockleys and sold out to a Citizen and Cutler of London (DE/HCC/27442) from which date the estate changed hands frequently until its purchase in 1813 by Enoch Durant (DE/HCC/27461) It was bought from his heirs and successors the Burdett - Coutts family in 1888 from whose representatives the County Council purchased it
Contents:
The earlier title deeds of High Cannons a mansion and estate of 800 acres at Shenley & Ridge in the Hertfordshire Green Belt acquired by the County council.
Small purchases bring in the title of Shenley Hill (DE/HCC/27570) and Salisbury Hall, Shenley (DE/HCC/27489) as well as The Grove, Watford (DE/HCC/27523) and Tyttenhanger, Ridge. It is interesting to see the close association of this area with the early private bankers
It includes .........................
Admission DE/HCC/27605 16th October 1730
Contents:
Of Thomas Wotton, Esq. to Pieces of land waste of manor,
part of which now converted into a fishpond, on road from Shenley Hill to Well End, etc. Manor of Shenley HallRegards
Ray