The only site where P. jenningsi has ever been found is a former clay pit now used for recreational fishing between Bretherton and Croston in Chorley borough, Lancashire [REF].
Prior to the discovery of P. jenningsi, there had only been four reports of freshwater nemerteans in the British Isles, in the River Cherwell at Oxford, the River Cam at Cambridge, a tank in Regent's Park, London, and the Grand Canal at Clondalkin, County Dublin [REF].