Bought two of the Middy ones and used one for the first time on Sunday and was very pleased with it, makes changing hook-links so much easier. Thank you all for the suggestions, I bear in mind about using it for hooking hemp, have tried it before just putting a hook into hemp, with the inevitable splitting occurring.
Totally agree with Tinca Steve another thumbs up for the Preston Knot Picker, it also has a secure screw top cover on the picker.
I bought the Browning knot Picker but unfortunately would NOT recommend them. The picker cover is only a push fit and not very secure, also the disgorger end is a wire type and fell out just after removing it from the packet. Very disappointing.