Idiot bus drivers

so no one has ever cycled to the left of stationary cars? Its the not the best tactic admittedly but getting out of a vehicle in traffic without looking isn't either.

Yes, and I've been twatted by a non-indicating left-turner.

I still undertake stationary cars, but slowly and carefully.

I wouldn't undertake a stationary bus because there's a much higher likelihood of someone getting off it. As you have found out...