Re: If Morrisons is liable for what an employee did ...
"at a cost to the company of having to deal with the extra franking and cash handling"
Well Franking costs pretty much nothing, and when you start charging for postage that probably costs as much to deal with as the cost of the post you are charging for.
I have always just put personal items like bill payments, etc in the corporate out tray and considered it as perfectly normal and reasonable to do so.