I'd definitely send National Express (who operate the Hoppa service) some feedback. I rather suspect the driver you came across wasn't one of their best...

I remember really confusing an Aussie barmaid in London with a Bank or Ireland issued Northern Irish banknote in the late 90s - this was before the Republic of Ireland joined the Euro, so her not unreasonable thinking was that it was a banknote in Irish pounds (puint) and was issued by the Republic of Ireland's equivalent of the Bank of England (which is in fact the Central Bank of Ireland), rather than a pound sterling banknote issued by the NI division of a pan-Ireland commercial bank.