My Basic Pay is £412.30 as a full time OPG but only £346.78 is pensionable - I don't know why? Supplements and overtime are non-pensionable so RM save money every time they pay you like that instead of in your basic wage.
Here are a few figures highlighting the fact my pension was only paid on 64% of my last pay packet (red figures have changed from actual payslip)
It is interesting to see that if RM used 100% basic pay they'd only be paying about 13% and if O/T were included it would cut their payments further - but we'd be taking the hit from the extra pensionable pay.