Changes in British English pronunciation during the twentieth century

The consonant system of three pairs of plosives (p,b;t,d;k,g) four pairs of (supraglottal) fricatives (f,v; θ,ð; s,z; ʃ,ʒ) a pair of affricates (ʧ,ʤ), a trio of nasals (m,n,), a glottal fricative (h), and four approximants (a pair of liquids and a pair of semivowels: l,r; j,w) was in the twentieth century the most stable part of the English phonological system, having remained the same for centuries.