As
@moonsafari has already said in her very informative blog, there were one or two of the regulars / staff at the Nags who had a limp of some kind. So the person in Heworth Place could either have a limp or fake one so as to incriminate someone else.
As we know, the police did enlist an expert with particular skills at identifying "gait" this must be important to them.
What the police need is someone to come forward and say "That's my xxxxx and he was out really late that night-Oh my god"
What they don't need are loads of people coming forward with stupid theorithat have no grounding and zero facts.