UK state pensions obey the so-called 'Triple Lock' rule where they increase in payout yearly according to the greatest of: 1. the growth in national average earnings; 2. the growth in retail prices as measured by the Consumer Price Index; 3. 2.5 per cent.

This causes an additional increase in pension costs over time on top of the effect of the country's aging population and is a source of resentment among some young people.