<P> The Sub-inspector (S.I.) is a rank used extensively in South Asia: in the Bangladeshi Police, Indian Police, Pakistani Police and Sri Lankan Police, which is primarily based on the British model . It was formerly used in most British colonial police forces and in certain British police forces as well . The rank usually was in charge of a police substation or assisted an inspector . </P> <P> The rank of sub-inspector was introduced into the Metropolitan Police in the late 19th century . It did not last long, being effectively replaced by station sergeant in 1890 . Officers who already held the rank retained it, and were promoted to inspector as soon as a vacancy arose . </P> <P> Sub-inspector was introduced into the RCMP from 1942--1960 with the insignia of one star, similar to an Army second lieutenant . </P> <P> The rank of sub inspector was replaced after the Rhodesian Unilateral Declaration of Independence with three grades of Patrol Officer, Senior Patrol Officer and Section Officer with one, two, and three gold coloured bars respectively . </P>

How to be a sub inspector of police