Butcher's was Cockney rhyming slang, used in constructions like "'ave a butcher's at this", which meant "to take a look" at something. In a Cornish churchyard, Ben once told Polly to "'ave a butcher's" at a grave from 1592. (TV: The Smugglers)
Behind the scenes Edit
The implied rhyme is between look and "a butcher's hook". But as with most rhyming slang, the word that rhymes is dropped in preference for the one that doesn't.