An enforcement warning notice (EWN) formalises the process whereby a local planning authority (LPA) can invite a retrospective planning application for unauthorised development. An EWN will set out details of an alleged breach and state that unless an application is made by a certain date, further enforcement action may be taken.
There is no right of appeal and the service of an EWN can trigger 'second bite' provisions giving an LPA longer to enforce against the alleged breach.