Here is an Alexander Whitcher with a father Isaac Whitcher, did he marry again after being widowed to Mary? Or is this a different man??
1856 Alexander WHITCHER full age widower Gardener Porchester & Sarah MATHEWS full age spinster Porchester both signed fathers Isaac WHITCHER Yeoman & Thomas MATHEWS Yeoman in the presence of Henry James LEIGH & Elizabeth LEIGH
Porchester is in Fareham, Hampshire. Yeoman again I am afraid!
http://www.knightroots.co.uk/transcriptions/Parishes_P/Portchester/Marriages/marriages.htm1861 Census
Titchfield -Hampshire
WHITCHER Alexander Head M M 60 Licensed Victualler Hampshire - Eling
WHITCHER Sarah Wife - F 42 Hampshire - Portchester
WHITCHER Harry Son - M 14 (born 1847) Middlesex - Chelsea
BRAZIER John Lodger W M 50 Blacksmith Essex - Maldon
LOVEL Frederick Lodger U M 35 Ag Lab Hampshire - Eling
Son Harry Witcher born up in Chelsea, Middlesex. Looks like your Alexander
If Mary Witcher died in 1849, then Harry's GRO registration should give Mary's maiden name?