Thanks Jonathan, I have sent you some pictures.

As you will see once the pictures are posted up, the clamp screw has an extended tab in order to tighten / undo the clamp without an allen key.

The bipod spring has caught on the tab and bought off the black finish and I have also Used my Leatherman Wave to slacken off the clamp with first taking off the bipod from the clamp.

In all fairness to Keith, it was I who asked for this design, which I am sure, is very much a prototype as regards the screw tab. If I had thought about it beforehand, I would have wrapped some black electrical tape around the spring to stop it rubbing on the tab (could also put some around the tab).

Overall, I am very pleased with this clamp.