It wasn't clever and it wasn't funny. Comic Jimmy Carr, who can be both, was entirely out of order with his quip about soldier amputees.
Mocking disability, especially horrific wounds gained in service of the country, should be off limits.
Too many comics use shock as a substitute for humour and are continually trying to push the boundaries of what is acceptable. It used to be that blue humour was the greatest risk of offence at a live show; now that is often just the jumping off point for comedians determined to plumb the depths.
Being funny isn't easy. Being offensive is.