The bus problem was a consequence of CO19 being assigned to do the stopping under the plan, and Dick's failure to change the plan when it turned out CO19 weren't in place. CO12 could have done the stop after he came out of the flat (this was the plan for ALL people exiting the block), and they could have done it at several points, right up until he went into the station. Dick nearly let them in the last minutes, but then countermanded, as she heard CO19 were arriving. Then they shot him.

The communications systems and structures also contributed, as central control didn't get full information and made decisions based on Chinese whispers. That's a Met issue rather than a Dick one, IMO. A local commander could have reacted tactically, and could have let CO12 act when they realised the plan wasn't working because CO19 wasn't there.