Something missing here... have Barclaycard given you a 0% balance transfer offer? Your post doesn't say so, but that seems to be implied otherwise surely there'd be interest to pay on most of the balance. I presume you'd also need to repay any fee first, unless they agreed 0% for that too.
Thereafter, I think it's just a question about the interest free period for purchases, which according to the Barclaycard T&Cs published 1 February 2016 (first Google result) is much more complicated than it used to be as they've split outstanding debt into lots of different types (main balance, standard balance, cash balance, non-promotional BTs, payment plan balance, promotional balance, etc).
Have a read and make your own mind up - it's sure to be fun. My interpretation (not intended as advice) of the terms effective on the above date is that the standard balance needed to be cleared in full to benefit from an interest free period, which seemed to mean all new purchases, previous purchases, non-promotional BTs and promotional balance... basically everything except the payment plan balance. However, check the latest T&Cs as they'll no doubt have changed so could be more favourable to the situation you describe now. The online Barclaycard help says they'll post your personal T&Cs within 10 days on request if you don't already have a copy.
Oh, you already followed-up whilst I was replying, but nevermind, I'll post this anyway!