The campaigner is setting up her own index tracking the price of the basic ranges at supermarkets with the help of an army of Twitter followers, known as the Vimes Boots Index, in a reference to Discworld author Terry Pratchett.

She said was “delighted” by the ONS’s inflation overhaul but it is understood that the statistics body will not be publishing its own index of basic ranges envisioned by Ms Monroe. 

Plans to use the much broader supermarket scanner data have been in preparation for months, allowing the ONS to analyse switching between products such as branded and own-label baked beans. 

Mike Hardie of the ONS said the move would give officials “even more detail on how inflation is affecting UK households”. 

He added: “Even once we know how much of every item is bought, we would still need detailed information on exactly what products people in each income bracket buy to be able to produce truly accurate data on exactly how much of what is being bought by whom.”