Wallabies have been running(jumping) wild in the peak district for many a long year.
Extract from wikipedia "Wallabies are widely distributed across Australia, particularly in more remote, heavily timbered, or rugged areas, less so on the great semi-arid plains that are better suited to the larger, leaner, and more fleet-footed kangaroos. They are widespread in New Zealand, where they are often hunted. There are also a few populations of wallabies in the British Isles, the largest of which can be found on the Isle of Man where there is a breeding colony of around 100."
It's a load of rubbish. To get any effect from the sap exuded by poppy seed heads it has to be heated to concentrate it then ingested by smoking or eating. You can't get "high" by mearly running through a field of poppies.