The Incident Officer (IO) is responsible for the efficient, safe running of the incident team.
At the start of the day the IO will pair up incident marshals & decide, in cooperation with the Post Chief, where to position them for the most effective handling of incidents. At bigger incidents the IO will decide how many marshals are needed & how they can best handle the incident.
IO exists as a separate grade, but in many cases the duties of the IO will be performed by an experienced incident marshal.
Some circuits do not use IOs & at Silverstone the IO's role differs from the norm at other circuits.