All assumptions used in the calculations are explicitly set out in the article. What do you think is missing exactly?
Any and all mention of the different PS pension strands, there are 4.
He seems oblivious to the fact that the people retiring now on full service are those who were hired before 1995.
He hasn't, not once, mentioned the significant changes in the pensions (hence the 4 strands above) scheme that have been introduced.
As I said, it's no wonder he didn't put his name to it.