Green’s Dictionary of Slang

1. a thrashing.

1895

Mirror of Life 14 Sept. 6/4: The old 'un is now on the track of the Marquis de Bibbero, and after giving the poor old swimmist a coating, old Fred offers to match his youngest daughter, ten years of age, against the old man.

2. a scolding.

1956		J. Curtis Look Long Upon a Monkey 100: Did you good to give a bloke a bit of a coating; made you feel somebody.
1975		‘P.B. Yuill’ Hazell and the Three-card Trick (1977) 22: It was the first time Dot had given me a real coating.
1989		J. Morton Lowspeak 41: Coat – to tell off, or to scold, as in ‘I gave him a right coating’.