If the current seat post is 27.0mm and it fits well then it must be 27.0mm. It couldn't be forced from 27.2mm to 27.0mm because 27.2mm is larger than 27.0mm...
@VanUden started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
If the current seat post is 27.0mm and it fits well then it must be 27.0mm. It couldn't be forced from 27.2mm to 27.0mm because 27.2mm is larger than 27.0mm...