O.K. I'm clear that what we in the UK call a prawn, is a Shrimp in the US, I've often eaten them. But does a prawn exist in the US and where does it fit in the scale of crustaceans?

Ah, it wasn't the "prawn" bit that my colleague misunderstood -- he's bilingual enough to know about the prawn/shrimp situation -- it was the "cocktail" bit. It turns out that there's a common American restaurant dish called "shrimp cocktail" where the sauce is completely different, made mainly of chilli sauce and horseradish. I can understand the disappointment of anyone trying to order this and being served with the utterly genteel English version.

Peter