The Home Office view for land based incidents involves three levels of command and control, namely, operational, tactical and strategic.
Operational control is with the individual emergency services on the ground.
Tactical control comes into operation when two or more services are involved and is usually exercised by the Police force. Strategic control comes into operation when there is a major incident involving more services, e.g., the addition of local authorities such as highways and housing authorities. The key note is always co-ordination rather than command. There are two reasons for this. The first is that there are only very limited powers to give direction.