Price indices for pensioner households are published in Tables 7.4 and 7.5 of the Office for National Statistics (ONS) Focus on Consumer Price Indices. This information is available in the Library.
ONS produce separate indices for one and two pensioner households where at least three quarters of the household’s income is from state benefits. These households are excluded from the Retail Prices Index (RPI).
The ONS exclude housing costs from the pensioner indices on the grounds that this would overstate inflation, as pensioners either tend to have lower housing costs, or would mostly be cushioned against some rises in housing costs by increases in housing-related benefits.