In today's lower interest rate environment, 9% per annum would be at the upper end of the range of late retirement factors.
As Don says, you would need to check the scheme rules to see if they permit late retirement for deferred pensioners. Revenue practice allows you to defer drawing deferred benefits until you have retired from your last employment (or age 70 if earlier), but this doesn't oblige trustees to provide this option to members. Have you received a leaver statement from your old pension scheme? This may contain some information about early/late retirement options.
In general, I would expect trustees to be prepared to agree to allow you to delay drawing your benefits until you actually stop working (within reason), provided they can do so on a basis that is no worse than cost neutral to the fund. However, you won't know until you ask and they may not be prepared to give a commitment now as to how they (or their successors) might act in 15 years time when you reach age 60.
Regards
Homer