Acknowledging all the concerns about speculation etc but, this is what Pprune is here for.
If one lines up the crash site on google maps with the tower crane, then extend it northwards, it lines up perfectly with a route that takes you down the RHS of the River Thames (if flying south) past the Houses of Parliament inbound to Battersea. This would undoubtedly be an appropriate point to contact the heliport, so eyes down onto the radio (single crew operation) to change frequency, whilst in and out of the mist and very easy, with the River quite narrow, to miss the right turn, especially in reduced visibility. It would only takes seconds to cover those hundred or so yards.