Green’s Dictionary of Slang

lit. or fig., a beating.

1999		J. Cameron Brown Bread in Wengen [ebook] [We] gave the booze some welly.
2003		N. Griffiths Stump 184: We’re just gunner shit the fucker up, that’s all. Just say boo. Birrer fear, birruva welly.
2004		N. ‘Razor’ Smith A Few Kind Words and a Loaded Gun 71: So Pete jumped in, threw the car into gear and gave the accelerator some welly.