Question Author
Solved it!
one needs a very long screwdriver and a hammer. You have to prise open (sorry, hack off) the daft antitheft device, which is plastic and then, once it has dropped you can shaply tap the locking spring with the handy long screwdriver and hammer combo.
On the 02 model I've got you have to tap the spring through the front grille; however older (& newer) models can be accessed from underneath.
Thanks to all for the advice. I hope this forum will help some one else with this dilemma. It will take longer to do than you'd think.!