Throughout the debate over public sector pensions one particular page of the Lord Hutton's report on the issue has been pivotal.

Unions have frequently pointed to a graph on page 10 of the interim report which suggests that the cost of public sector pensions will fall in the coming decades as a proportion of GDP.



This, it is claimed, shows that these pensions are affordable in the long run, so didn't need the reforms now being put in place by the Government.

However, it seems this is not the interpretation of the man who wrote the report containing the graph.

“The fundamental mistake the trades unions are making is that the chart assumes that the reforms have taken place,” he told the Financial Times. “They are the post reform costs.”

He added that trade unions were "torturing the data until it confesses."

Full Fact has already investigated the claim and found that Lord Hutton's point is a bit contentious.

The Government Actuary's Department, who produced the graph, explained to us at the time that it does include some reforms to public sector pensions such as the switch to CPI inflation instead of RPI for indexation, and an increase in contributions were factored into the calculations.

But while it does factor in the savings from some of the reforms aimed at reducing the cost of pensions, it did not necessarily include all of them.

We were told that the graph included the savings to pensions payments under the cap and share scheme, which in the Pre-Budget Report of 2009 were announced as £1 billion per year from 2012/13.

But last year's Spending Review talks of delivering “changes to the level of employee contributions that will deliver an additional £1.8 billion of savings a year by 2014-15.”

This is best explained in the chart below which shows the savings from pension changes as set out in the 2009 Pre-Budget report and last years spending review. The Spending Review figures come from Table 3 and Table A.3

	2012-13	2013-14	2014-15
Pre-Budget report 2009	£1 billion	£1 billion	£1 billion
Spending Review 2010	£160 million	£1.27 billion	£1.76 billion
Total (From SR 2010)	£1.2 billion	£2.3 billion	£2.8 billion

So if the graph really does just include the original figure for cap and share, and not the additional savings, then it is not all of the planned changes that would be worked into the graph.

This is where the question of timing becomes a bit tricky. The graph in its original form appeared on October 7, and additional savings in the Spending Review were announced 13 days later.

Logic would suggest that the Hutton report couldn't have factored in changes that had not been announced.

That he was kept informed of Treasury thinking and factored this in is another possibility, although there is no hint of this in Annex C of the interim report ,which explains the graph.

So while it makes sense that the man whose Commission published the graph in question knows most about what it does, or doesn't include, the information we have seen suggests this hotly contested chart includes some, but not all of the reforms being implemented.

So what the graph actually tells us about the affordability of public sector pensions will continue to be a  hotly-debated point