newspaper notice of marriage from 10 April 1828
on Monday, the 7th instant, at Knaresborough, William Wainman Esq., of Wood Hayes, Cheshire, second son of the late William Wainman Esq., Carhead, Yorkshire to Jane, daughter of Thomas Atkinson Esq., Upper Montagu Street, Montagu Square, London.
So William was related to the Wainmans of Carrhead, but descended from a second son, and the estate would have gone to the oldest. Second son went into the Army, not unusual.
There's an obituary in the Naval & Miltary Gazette for the William who died in 1866
'3rd (The Buffs) Capt. William Wainman, formerly of this regiment died at Bayswater on the 14th inst. The gallant deceased was the elder son of the later Major Wainman of Woodhayes hall, Cheshire. He entered the service as Ensign, Dec 12th 1851, and became Lieutenant June 6 1854. He served at the siege of Sebastopol in 1855, for which he received a medal and clasp, and became Captain 1 Feb 1856.'