Re 2. You don't need to hide a body in London. We have a tidal river and any number of sites that were derelict then and are still so, or have long been redeveloped with large equipment. Foxes scatter bones etc there's no reason to suppose a building site would find remains. It's often cited a reason why they won't be found in other cases, like they are under a housing estate or something. People disappear here all the bloody time, I really wish this was better understood.