A good condition Middlesex Area Ambulance Service 2nd pattern 1950's to 1965 one piece chrome enamel cap badge manufactured by J Pinches & Co Badge Company with both cap fixing lugs intact to the rear of the badge. Middlesex ceased to exist as a county in 1965 when swallowed up by the new Greater London Council which expanded in 1965. The first pattern Middlesex Ambulance Service cap badge was also issued to the Middlesex Fire Brigade & was worn until the 2nd pattern blue shield cap badge was issued in the mid 1950's. 
Ambulance Services in the U.K formed after WW2 when an act of parliament was passed , The National Health Services Act 1946 which was set up to provide a health service to the whole of the U.K. It came into being on 5th July 1948 & lasted until it was replaced by The National Health Services Act 1977 !!
Initially ambulance staff were volunteers, The Milar Report of 1964 changed that, making a recommendation that patients be treated en route to hospital. Training Schools were set up & recruits were trained in basic 1st Aid & other extended skills in the use of oxygen, Entonox etc, the cap badge they wore was a laurel leaf !
In 1974 the ambulance services transferred to The N.H.S & the retro cap badges of 1974 replaced the earlier badges. These were again replaced in the late 1986 to the laurel wreath with the Q.C, these badges being mainly gilt enameled & termed as “ modern cap badge !