In Northern Ireland it is very common to use surnames as Christian names for both males and females. I know of Hamill, Blair, Craig (female), Acheson, Whiteside, Moore, Hamilton, Smyth, Pollock, Knox, Irwin... all used as 'Christian names.'
Sometimes a person is named for someone and given both their Christian name(s) and surname. If a child was called Alexander Shaw Armstrong he might have been known as Alexander in school and on a marriage certificate but as Shaw on other occasions.