My goal is to examine acoustic and perceptual data from various locations in the British Isles – Enniskillen (Ulster), Glasgow, and Hull – in order to better understand the production and perception of certain Derived Phonological Contrasts found in English. This research falls within a broader framework that I call the Gradient Phonemicity Hypothesis (GPH), according to which a whole range of cognitive statuses is assumed to exist between allophony and phonemicity, and a difference between two sounds can be described by some measure of how typically allophonic or phonemic their relation is. In addition to the well-known attributes of maximal phonemicity – e.g. phonological unpredictability, high functional load/type frequency, etc. – it is my contention that a more thorough understanding of gradient phonemicity can be gained by analysing acoustic, articulatory and perceptual data.