Squire was a title. Typically denoting the assistant of a noble of higher rank, it was also used as a mere title of nobility in England.
Bostock served as squire to the knight Orcini of the Grand Order of Oberon. (TV: Revelation of the Daleks) During the Last Great Time War, the title of the Squire was adopted, in the vein of the Doctor and other Renegade Time Lord's noms de guerre, by a member of the Volatix Cabal who fought at the War Doctor's side. (COMIC: The Then and the Now)
The eldest surviving male member of the Holmes family, Sherlock Holmes's eldest brother Sherringford Holmes held the title of squire and took care of the old family farmstead in Yorkshire. (PROSE: All-Consuming Fire)