How to lock a Pashley Guvnor?

If your main concern is weight, isn't this i pretty heavy?
I worked in a bike shop for a bit and built a couple of Pashley's, from what i remember they weighed a ton?

old horrible design from the 50's, no surprise there!

in all honestly, I somewhat doubt thieves realise that they can take off the rear stay by a few turn of an allen keys.