 An exception to the above is the City of Westminster borough.Westminster has over 1,500 officers therefore a three digit number system is too small.Until late 2009 constables and sergeants had four digit shoulder numbers beginning 1, 2, 3 or 4 (with the leading number signifying which part of the borough you were attached to - 1 Westminster North, 2 Westminster Central, 3 Westminster South or 4 Westminster HQ).