I wouldn't sweat it. The Met Police is divided into 12 Basic Command Units (BCU). Number 3 - South West BCU includes the London boroughs of Kingston, Merton, Richmond and Wandsworth. The Richmond area includes Barnes which borders Putney, which comes under Wandsworth.
AC is missing from his home address in the Richmond/Barnes/Putney area.....they are very close together. His home address obviously falls within the Richmond policing boundary so for policing purposes that is where he is missing from. Therefore, Richmond police create the missing person report and are responsible for the investigation.
Yes I know he was last seen in Bow Road, but imagine if Tower Hamlets reported him missing from Bow Road, then there was a confirmed sighting in Oxford Street, London, W1, covered by Westminster. It would be impractical to keep transferring a missing person report for so many reasons.
So 'missing from' is not the same as 'last seen' . I hope that is as clear as mud