If the door is made of wood a simple 'attach' with a screwdriver will expose enough space to do the credit card thing on a Yale lock.Nothing wrong with Banhams - although a bit pricey -but why not use our local locksmith, Acton Locksmiths on the A40 just up from Dreams. They have full range of mortice locks and will come out and fit them if you want. I have used them and found them to be good.
Charles Gallichan ● 5796d