I could be wrong here, but I would guess that the phrase in question is
A. Of Yorkshire origin, and
B originated as the catchphrase of some comedian, in the days when you had to have a catchphrase. If you were a comedian, that is. Although there was no reason not to have a catchphrase even if you weren't a comedian.

LtS's explanation abaove explains exactly what the phrase means.

My ex-mother in law used to say this in her beautiful Yorkshire accent. She also made heavy use of the phrase "daft as a brush", which I never really understood ............

Murray