 With the amalgamation of Westminster Central and South in late 2009 the decision was taken to amalgamate all the shoulder numbers into one numbering system.All new officers joining the borough will be given the first available number and cross division moves will no longer result in the need for a new shoulder number.Specialist MPS units do not necessarily follow any of the above numbering rules, with both Constables and Sergeants having anything from one to four digits.