Did they saw/crop through the lock or the cast iron to relieve him of his wheels?
A good dunt on some old cast iron is often enough to shatter it. Failing that, you can usually cut through it pretty sharpish with just a hacksaw.
If someone would like to come and steal the abandoned bikes in our stair that the neighbours refuse to move, despite never having moved them in 3 years and not being in a ridable condition, apply within for details. The other neighbours who do cycle would prefer not to have to leave their bikes in the back garden.