A hiking trail in northern France through land owned by the family of John Kerry, the former US Secretary of State, has been opened to the public after a bitter 37-year legal battle.

Applications to open the scenic path along Brittany’s breathtakingly beautiful Emerald Coast had been opposed by Mr Kerry’s cousin, Brice Lalonde, a former French environment minister who is also a champion of green causes.

Criticised for “hypocrisy” in seeking to keep the trail closed despite right-of-way laws allowing public access to coastal paths on private land, Mr Lalonde, 73, insisted that his only concern was a potential “terrorist threat” to the former US secretary of state.

But there is deep local anger that thousands have been denied spectacular views because of a handful of rich proprietors who only visit the area for a few weeks each year. Patrice Petitjean, the head of a hiking club, said: “People had been growing impatient. They were tearing down the barriers to get in.”

Mr Kerry, 75, who speaks fluent French, has often holidayed at the Essarts estate which the trail passes through. The estate is owned by the Forbes family of which he is a scion.

Mr Lalonde served as mayor of Saint-Briac-sur-Mer, the local commune, for 13 years. His critics say this is partly why this dispute has taken so long to resolve, an accusation he denies.