Folded and purchased it from CDkeys, I saw it had regional restrictions (i.e not India etc) but despite having not changed my store from the UK and GBP since living overseas (I travel too much and use my laptop for steam when overseas) I wasnt able to activate it.
IP address issue maybe? Never had this problem before with regionally restricted games whilst living overseas.
I wont ever risk using a VPN to activate steam titles, so in the end requested a refund and purchased it elsewhere (truely global key) for about 28 quid, activated fine.