@Martin ****
did i say he'd be blacklisted? No, I didn't. He is more than welcome to pay an overstay fee at the airport if he wishes. Will the stress of dealing with that and any consequences of being stopped by the police in that short period of time between visa expiring and departure be something the OP is fine with? Only he can say. Financial saving of paying a couple of days overstay vs spending a few minutes getting a tourist visa to cover his entire stay that will guarantee no possible issues with boarding in the first place, to me, isn't worth it. Seems like a lot if risks for a £10 saving