Most butty fillings require a top slice to keep them i place, but a jam buttie can be open. To get the best out of it, you should use strawberry jam and dig out as many whole strawberries as possible without your mother seeing you, and before your brother can beat you to it. You get extra marks if you use up all the strawbs in the jar. The bread, ideally, should be hand-cut from an unsliced white loaf (brown bread is for cissies and girls), and as thick as is practicable for the size of your mouth: for an open sandwich, two inches is probably a but too much, unless you're a singer. The actual cutting method isn't important. I favour the vertical parallel-sided method, which I'm particulary good at, but if you go for the under-the-arm style, you lose points for cutting off your own nipple, however much it might look like a strawb (unless it's for your brother).

Anyone remember Marlon in the Daily Mirror, with his inch-thick ketchup fillings? Definitely a good one for a crowded tube train, but make sure you have your back to the door and practice your timing.

Steve