This was interesting...
Bus lanes that motorcyclists can legally use
Kingston
• Kingston Rd / Cambridge Rd
• London Road
Richmond• London Road, Twickenham
• Eton Rise / Paradise Rd, Richmond
Westminster• Cockspur Street - Eastbound
• Kensington Road / Kensington Gore - Eastbound
• Baker Street / Portman Square / Orchard Street
• Haymarket
• Bayswater Road
• Kensington Road / Kensington Gore - Westbound
• Piccadilly - Eastbound
• Gloucester Place - Northbound
Trial sites on the Transport for London Road Network• A13 East India Dock Road (between Leamouth Road and Butcher Row East)
• A23 Streatham High Road/Brixton Hill/Brixton Road (between Streatham Common and Camberwell New Road)
• A41 Finchley
The ones on the A4 in Kensington and up to Hyde Park Corner would be handy too...