I have never seen a Leech before, although they are reported to be common. This photo was taken at a shady muddy pond in Centre Vale woodland at Todmorden I fished out an old Beech husk that seemed to have moving legs and found 2 Leeches underneath. Only about 10mm long but it quickly extended its body when it saw me looking at it! On closer inspection the whole pond was teeming with them.

Are they common in the valley?