Hi scintill, thanks for your reply.
Pretty sure there is no bad whitespace added. See this album of screenshots showing what I'm doing:
http://imgur.com/a/dqW9QJust selected the private key from my forum post again and pasted into the import window.
Re: the wallet address, as this isn't a deterministic wallet my understanding is that I need to supply the wallet address also? Otherwise the wallet address could be anything?
Cheers,
Matt.