I think there may be some confusion with regards to dates on this thread and what happens when. My understanding having read the relevant leaflets is this;
Anyone aged over 45 on 1 Apr 12 will remain on their current pension scheme (75 or 05) until they retire, their benefits are unchanged. Everyone else will automatically transfer onto the new scheme on 1 Apr 15 (current planned introduction date) and pension rights accrued on their old scheme up to that date remain payable when you retire.