Should there be a tax placed on throw away coffee/tea cups?

A tax could help, but I'm not sure that people will honestly notice an extra few pence on the price of their extremely expensive latte. If you'r already paying £3.50, would you refuse to pay £3.55? Probably not. But then again, the plastic bag "tax' worked quite well, and people thought twice about paying that extra 5p. Perhaps if it was framed in the same way - "And would you like a cup for your coffee, for an extra 5p?" it might work. Some places do already give a discount if you bring your own travel mug. This whole thing could be extended to drinking straws, disposable cutlery, etc.