Green’s Dictionary of Slang

(orig. milit.) to lose one’s temper.

1925		(con. WWI) Fraser & Gibbons Soldier and Sailor Words 140: Lead Off, To: To be angry: to lose temper.
1937		J. Curtis You’re in the Racket, Too 61: To hell with you and the landlady. You’d think she was made of gold-plate or something the way you keep leading off about her.
1942		G. Kersh Nine Lives Bill Nelson 4: This old geezer’s leading orf about ’er Georgie this, and ’er Georgie that.
1950		C. Harris Three-Ha’Pence to the Angel 197: And now it’s no good you leading orf, making your own life and everybody else’s a misery.