They are attested as constables under Article 18 of the Ministry of Housing and Local Government Provisional Order Confirmation (Greater London Parks and Open Spaces) Act 1967 before a City of London magistrate.
The Heath Constabulary continue to use the term "Constabulary" rather than Parks Police to portray a more local and traditional aim of policing, but for those who are confused by the term the words "Policing Hampstead Heath" have been added to their vehicles to clarify their aim.