Index linking of OAP depends on country of emigration, for instance Canada no and USA yes. Similarly OZ and NZ no, but EU etc is yes.
I am not sure about the Caribbean Islands (ex Colonies) but I think they are OK as the index linked policy is based on reciprocity.
http://www.thisismoney.co.uk/money/p...-overseas.html
http://britishexpats.com/forum/austr...nsions-155113/
Once you are permanently abroad then you should not be paying UK tax.