I agree. The only way L cannot have left the park, yet not still be within the park, is to have been carried out via flowing water. Remember the forensics, red flags and photography on the stone boathouse steps? I think they've found some clue there which suggests L went in the water, but police need to prove it wasn't suicide by linking PR to the scene via disposed clothing or signs of a struggle or cover-up.
Croda running man could be PR leaving the park for the second time in a change of clothes (light top, dark trousers), having ditched his wet/soiled hoody and jogging shorts after tipping L's body in the river. He couldn't explain the disappearance of the Haworth CCTV hoody and shorts from his wardrobe, so that's what they are searching for in the park, along with perhaps his glasses. His defence is that he left L crying and depressed at the bench.
I'm still open to running man number 1 being PR leaving the murder scene for the first time, still in his original clothes ie not "dressed for the weather" - but the timings are very tight to fit with the witness account. He needs to leave Haworth 12.09, drive straight to park, murder L (12.15-12.30) then exit the park (12.30). Then he has 45-minutes to fetch a change of clothes from car or house, return to the park and dispose of evidence, before jogging into view at 13.13. Hm.