As always, jamesnan, the devil will be in the detail which has not yet been published (or perhaps even thought through).
However, as I understand it, the new guaranteed amount (which is variously reported between £140 and £155) will only apply to those people who reach pensionable age after the new scheme is introduced (which is currently planned for 2015 or 2016.
The basic State pension by then will probably be around £115. Anybody reaching State pension age the day before the new scheme is introduced will receive this amount and they need 30 NI Contributory years to qualify. Anyone reaching pension age the following day will receive the new rate (up to £2,000 more per year) and (again as far as I understand) no NI qualification will be necessary.
We already have a two-tier state pension scheme (disregarding those who receive a “pension” having never contributed a penny). There are those who have their pension payments based on needing 39 (for a woman) or 44 (for a man) contributing NI years. Those with less have their pension reduced. Then there are those who qualify for a full pension having only contributed for 30 years. And now we will have a third category of those who will receive the new full amount, considerably in excess of the current rate, who may not have contributed anything like 30 years.
And that, we are told, is “fair”.