Advice on planning DIY Perms in England, reproduced from the Audax UK website
Tiers 1 and 2: 6 riders per event route per day, 600k upper limit on distance. Only minimal entry into one Tier 3 area is permissible. Riders should not stop in that Tier 3 area. No routes should enter Tier 4 areas.
Tier 3: 6 riders per event route per day. Maximum distance 200km. Routes may pass through one adjoining Tier 1-3 area but riders should not stop in that adjoining area.
Tier 4: 2 riders per event route per day. Maximum distance 200km. The whole route must be contained within the original Tier 4 area. (Note: as per published Government guidance, the 32 London Boroughs and the City of London comprise one area for tiering purposes and the same will apply to the Tier 4 area of Essex and the Tier 4 area of Surrey).