OAP
If you leave before 60, your '15 benefit is an EDP stream, which only becomes a pension in payment at your state retirement age. At that point, you can convert up to 25% into a lump sum. It won't be much for most reading this.
If you don't serve until 60, your accrued deferred '15 benefits have already been quietly linked to the state retirement age anyway. So, preserved '15 benefits will be shifted to the right automatically if (when?!) state retirement age also shifts to the right.
Top of page 11:
https://www.gov.uk/government/upload..._FAQs_V140.pdf
Interesting(ish) for those retiring to the Channel Islands: Guernsey has recently raised its state retirement age to 70 (as well as other measures).
http://www.gov.gg/CHttpHandler.ashx?id=94029&p=0