Sainsburys, petrol and diesel

How often Sainsburys changes its prices is not here. We read every six hours, so a change made and reversed inside that window leaves no trace. Any frequency would undercount.

The gap to the national median is not a policy. Brands sit in different places — motorway sites, city sites, supermarket forecourts — and the mix moves the median on its own. This page compares what was published, and stops there.