So it was refreshing, on a recent flying visit to England, to come across this sign on Black Down in Sussex.

The English Downs are described by my computer's dictionary as "ridges of undulating chalk and limestone hills, with few trees and used mainly for pasture".

However, Black Down has not been a down in living memory.

With the urbanisation of Sussex, a 40-minute train ride from central London, grazing stopped and the down became a forest whose main inhabitants were walkers from the leafy network of peri-urban villages surrounding it.

Then that remarkable institution, the British National Trust, exercised its zeal for historical authenticity and a certain amount of courage, and attacked Black Down with bulldozers.

A few dozen acres of trees were flattened, and a small mob of Angus "conservation cows" introduced.

The idea is that the cattle will stop tree regrowth, and that hillside meadows will eventually flourish again on Black Down.

Sadly, I don't think that the National Trust has been reading Alan Savory or Andre Voisin. The concept of high impact, short-term grazing followed by a long rest doesn't seem to be part of the program.

My impression was that these cattle are on the job full-time. That means that they snack repeatedly on the palatable plants, which eventually give up the ghost and disappear, while the blackberries, heather and other less tasty species get a free run.

It's a sequence that has seen big tracts of Australia go to the weeds.

As I picked my way through the blackberries and heather and Angus, and looked in vain for the early signs of meadow grasses, it seemed to me that the wrong sort of succession is well underway on Black Down.

I won't argue that cattle can be a destructive species. If NASA ever wanted to cost-effectively test a new spacecraft, for instance, it could just leave it in a paddock full of steer weaners for a week. If the steers hadn't licked, rubbed, trampled and crapped it into rubble within a few days, the craft would be fit for intergalatic travel.