Took me ages to find them in 1871!
1871RG10/1013 57 30
Western Heights, Kent
The Shaft Barracks Jane Brich, wife, mar, 24, Soldier's wife, b. Scotland
Richard Brich, son, 4, soldier's son, b. Lancashire Liverpool
William T Brich, son, 2, Soldier's son, b. Kent, Hythe, England
Robert C Brich, son, 4 months, soldier's son, b. Kent, Dover, England
and
RG10/1013 48 11
Western Heights, Kent
The Shaft Barracks Thomas Brich, head of family, mar, 31, Over Sergeant, b. Lancashire, Liverpool, England

(looking closer at the 1881 census image, their surname looks like Brich as well! BMD say Birch however)