Keep to the footpath ?

Photographed near the town of Burnley in Lancashire, North-West England. After walking up to Crown Point and the "Singing Ringing Tree" (see my "Sony RX100" album) we decided to take a short-cut back to the town. My GPS showed this route (correctly) as a public footpath but gave no indication of how hazardous it was. There are lots of hidden rocks, holes in the ground covered by long grass and sudden steep drops down to the river which are not visible until you get to the edge of them. The so-called "footpath" itself is invisible beneath the grass and vegetation. This sign is located about half-way along the route.....I think it would have been much better if it was located at the start as a warning !!