There are 2 membership sections, namely deferred (aged between 25 and 64) and current (aged between 65 and 89). The charts refer to “def” and “pen”. A third section is 50:50, called “mix”.

Both sections have a total initial total pension of £1 m pa.  Mortality is zero until age 90, when all pensioners die immediately after a pension payment.

The weighted mean ages are 50 for deferred pensioners and 74 for current pensioners. When deferred pensioners retire, they are still classed as deferred, remaining withing that group (the calculations allow for the benefits being paid).

For current pensioners (charted here), the mean payments start at 1.00 in year 01. With RPI increases, the final payment in year 15 is 1.14, the total amount paid being 16.86. Without any increases, the final payment in year 15 is 0.62, the total amount paid being 12.58.
 
For deferred pensioners (charted here), the mean payments start at 0.03 in year 02. With RPI increases, the final payment in year 15 is 0.94, the total amount paid being 5.65. Without any increases, the final payment in year 15 is 0.51, the total amount paid being 3.65