lay (someone) a pound to a penny

lay (someone) a pound to a penny

To be convinced that something is very probable or likely (to happen or be the case). Primarily heard in UK. I've been hearing about layoffs and pay cuts for a while now, but I lay you a pound to a penny that none of the executives see a drop in their salaries. I'd lay a pound to a penny this issue was caused by a computer virus someone accidentally downloaded.
See also: lay, penny, pound