That 1881 census shows his address as Butchery Street.
There is a thread on RootsChat, from 2009, that has some info:
http://www.rootschat.com/forum/index.php?topic=385753.0So, it would seem that Butchery Street consisted of numbers of market stalls, all butchers?
I would therefore hazard a guess that "Butchery Keeper" was a sort of Caretaker, watchman or Supervisor?
In 1881 he would have retired from the Police Force, so a reasonable occupation for him?
In "The History of the County of Lincoln" is a mention:
The Butchery, in Butchery Street, was erected in 1774, at the expense of the corporation, and, though small, is very convenient.