"levering with a fork at right angles to the handle (whats it called?)"
Its a Canterbury Fork by Chillington Tools. I've succeeded in clearing a large area of brambles by slashing with a machete, burning, then you MUST pull up the roots, for which the Canterbury fork is excellent. Unless you dig up the root, they'll always come back. On wet soil (wait till after rain) the Canterbury is pretty easy and satisfying to use and its a 'final' solution. On our cleared area we've had a healthy new regeneration of bluebells, grasses, enchanters nightshade, sedge, dogs mercury, willowherb and several small Oaks. Brambles are valuable for wildlife in patches, but you don't want an impenetrable jungle of them suppressing everything else.