The bus driver was clearly in the wrong. You could write to TfL to complain and ask the operator to remind the driver of the Highway Code. Rule 163 really couldn't put it any clearer....
163
Overtake only when it is safe and legal to do so. You should
....
http://www.direct.gov.uk/en/TravelAndTransport/Highwaycode/DG_070314
163
Overtake only when it is safe and legal to do so. You should
....
- give way to oncoming vehicles before passing parked vehicles or other obstructions on your side of the road
http://www.direct.gov.uk/en/TravelAndTransport/Highwaycode/DG_070314