The UK’s statistics body said it has identified an error in the retail price index (RPI), which is used to calculate Government bond payments and changes in train ticket prices.

The Office for National Statistics (ONS) said that the RPI figures for six of the past 12 months were wrong by 0.1 percentage points.

It said the error was “caused by an issue with the 2018 to 2019 Living Costs and Food Survey dataset, which is used to produce the weights underpinning the RPI”.

“If the correct weights had been used, the impact on RPI annual growth rates would have been between 0.0 and 0.1 percentage points,” it added in a statement.

The RPI figure for July 2020 – 1.6% – was used by the Government to calculate the increase in rail ticket fares for commuters and travellers in England and Wales.

The ONS has now said that the reading for this should have 1.7% after the error was uncovered.

However, it said that the inflationary figure will not be revised, meaning there will be no knock-on impact to train ticket prices or bonds, in line with the ONS’s revision policy.

It stressed that the error will be corrected in the February release of inflation data, due on March 24.