Steve, you should read the report. It will greatly assist your participation in this debate.
The route, going West, is follow the North bank, not the river.
Eastbound is follow the South bank.
That's to limit the opportunity for a head on.
2.5.2 Flights on the helicopter routes
Reciprocal traffic on the helicopter routes is deemed separated when westbound traffic routes along the north bank of the River Thames and eastbound traffic routes along the south bank. Rule 5 applies, so any pilot routing along the south bank of the river and passing within 500 ft vertically of the top of the crane (whose elevation the associated NOTAM stated was 770 ft amsl), or the building (elevation 607 ft amsl) once the crane is removed, would be in breach of the ANO.
The building at St George Wharf has therefore increased the local minimum allowable altitude along the south bank to 1,100 ft (based on the building). It has consequently had the effect of preventing two-way traffic on H4 when London City Airport is using Runway 09 (when traffic on H4 is limited to 1,000 ft amsl) or when the cloud base is below 1,200 ft.