The average unit tour interval for the infantry and the Royal Regiment of Artillery is 23.5 and 20.8 months, respectively. This is calculated on the basis of the mean time between the start of the most recent deployment and the end of the previous deployment for all formed units within each arm.
The unit tour interval is a less relevant measure when applied to the Corps of Royal Engineers, the Royal Logistic Corps and the Royal Electrical and Mechanical Engineers. This is due to the frequency with which personnel move between formed units within these corps (which means that the personnel deployed with a unit will be substantially different from the personnel who deployed with the same unit on a previous occasion). Unit tour interval data for these corps is not therefore routinely collated.