A tip from an ARP4 owner. When using the parking brake to park, hold the footbrake down, whilst pulling up the handbrake lever, you will find that in most cases this will hold the car on most hills. It will not really do much to slow the car as an emergency brake though.
Get your MoT done at a Morgan dealer and they will (possibly) turn a blind eye to the fact that the handbrake is a little inefficient, although my car has been MoT'd at a normal garage to, who allow me to sit in the car to assist the tester and my foot may have strayed to the brake pedal, when the parking brake had to be applied!