Do you think Shelley was killed at the copse? I suspect she was because otherwise the killer has to carry her a fair distance through unfamiliar terrain, and also there's no obvious reason for Shelley's sandals to be there if she was killed somewhere else.
The general theory reported by the media over the years was that Shelley was murdered elsewhere and her body then dumped in the copse. A psychic told me Shelley was stabbed as she was getting into a vehicle. I have no strong view either way on whether Shelley was or was not murdered in the copse, but it is a discrete remote location.
The sandals raise alot of questions, including why leave them, if you apparently have taken everything else (bar tights) from the scene ? It is not uncommon for murderer's to re-visit scenes, so maybe they were left as marker ?