I live on the Island, and the footpaths have dismount signs around, but as it's not a cycle path or cycle highway, a dismount sign isn't require by law, as neither a sign for motor vehicle access is for payments. 

Under Rule 64 : Highways code, explicitly states that: "You MUST NOT cycle on a pavement."
Laws HA 1835 sect 72 & R(S)A 1984, sect 129

https://www.highwaycodeuk.co.uk/rules-for-cyclists.html