Thanks, so Cressidas Dick has a clear line of political accountability, ultimately to the occupant of No 10. Perhaps that explains why the Met seems to be so reluctant to investigate any of the party allegations (to part answer my own question - the Met apparently have a hastily cobbled...
Standard political response to a crisis - set up an investigation with an unspecified time scale for reporting back - issue catapulted neatly into the long grass. Oh, and then accuse the accusers of playing politics!!