I've not been able to find out much about these clamps. They're marked KL30 and KL40. The nearest are the Bessey Klemmy HKL30 clamps, which are a very similar design, although my heads are plastic, and they are wood. Same clamping mechanism though. Grubby on the surface, but otherwise in good condition. There are four KL40 and two KL30.
The lot for £20 plus postage.
The lot for £20 plus postage.