I've had my answer from SPVA and it is as follows:
When you attain age 55, repayment of Resettlement Commutation will cease. Your service pension will revert to its original level of £XXXXX (from its current commuted level of £XXXXX - £YYYY where YYYY is your commuted sum pay back).
Annual increases will be added to the pension at that point.
If you remain re-employed in FTRS at that point, your pension will continue to be abated. The abatement will be deducted from your new level of pension.
The current level of abatement to your pension is £YYYY and it will continue at this same level throughout your re-employment, unless you change post, rank or commitment, wherein the abatement will be reassessed at the point of change (adjusted to inflation).
As an example, if you were age 55 today:
Your basic pension would be £ZZZZZ (which is £XXXXX adjusted by inflation)
Less re-employment abatement £YYYY
At this point you would recieve £ZZZZZ-£YYYY
which is raised by index linking and the removal of the commutation sum
Happy days, that would see my take home increase by £5k overnight in his illustration - it will be a lot more when I really do reach 55
CPL Clott