These particular Enamels paints, first appeared in the late 1950's and continued up until around the late '60's, until being replaced by the more popular Humbrol Range, which are the same paints but in a smaller tinlet, under the label of Airfix these paints contained lead, which was not suitable for airbrushing use, due to the mix ratio being in reverse and leaving a large amount of pigment in the airbrush bottle. These colours are generic and do not follow any BS or FS formula.
NOTE:- Thanks to Anthony for the tinlets used in the photo.