I don't think that picture is anywhere near accurate. If you look closely, you'll see that:
(a) the BC house label points to a spot nowhere near where it actually is
(b) the "Screams reported" is pointing to a spot in the bush well away from Rafting Ground Rd.
I think it is just a generic picture, with the general area annotated at each end of that line.
I really don't think that the screen grab can be used as an accurate indication of where the screams where actually heard.
Also, remember that the pointer may be intended to point to the house where the screams were HEARD - not the place where they were uttered. In fact, picking a direction may have been very difficult - a couple of screams heard through a window, and I don't know if any more were heard AFTER the witnesses went out into the garden.
If we're assuming, for the sake of debate, that Allison MAY have actually gone for a walk (although it is looking less and less likely that she did) then I really can't see her walking all the way up there. And while that could be said to be on the way to the BC Seniors' house (still a long walk away), then why would she go there, and why would she not take her car?
I can see her doing a walk over Boscombe Rd, or even down and around the showgrounds and Produce Store, then into Huntingdon along Rees Way (a popular walking and cycling track) then back and over Boscombe Rd to home. That would still be a reasonably stiff walk if that's what she had been intending.
I've added a couple of bits about where each of those pointers is.
