About hashes, pounds and hashtags...
I agree with Dwarf here... it's not a hashtag. A hashtag by definition is a word *prefaced* by the hash/pound sign, #. Don't be mixin' your terminology here, you hear?
Easiest way to distinguish between the English pound (£) and the American pound (#) is to call the one the Sterling sign (which the £ is after all... the Pound Sterling, thank you very much!)
Much easier than 'octothorpe' ;-)