We're back to where they could have been coming from. It depends if they came from the ORPF end. Maybe they didn't.
I can't remember if it was mentioned, but old Streetview shows several houses at that end of Oak Road. In satellite view they seem to have been demolished, at least the ones the far side of the Croda entrance. If they were there and inhabited two years ago, the couple could have come from there, so wouldn't have been near the ORPF. The only other thing I can think of is that they were coming off a work shift, perhaps cleaners at the Mecca, something like that.