I just acquired this old tin of Gallaher's Two Flakes and I'm puzzled how to open it?! How were you supposed to cut the top of these tins? The old style can openers with the sharp prong are useless as you don't have a ridge to wedge the blade... The only option I can think of is to use a heck saw, but the cut will too rough and it'll ruin the tin. Any ideas?