This study compares the duration and first two formants (F1 and F2) of 11 nominal monophthongs and five nominal diphthongs in Standard Southern British English (SSBE) and a Northern English dialect. F1 and F2 trajectories were fitted with parametric curves using the discrete cosine transform (DCT) and the zeroth DCT coefficient represented formant trajectory means and the first DCT coefficient represented the magnitude and direction of formant trajectory change to characterize vowel inherent spectral change (VISC). Cross-dialectal comparisons involving these measures revealed significant differences for the phonologically back monophthongs /ɒ, ɔː, ʊ, uː/ and also /зː/ and the diphthongs /eɪ, əʊ, aɪ, ɔɪ/. Most cross-dialectal differences are in zeroth DCT coefficients, suggesting formant trajectory means tend to characterize such differences, while first DCT coefficient differences were more numerous for diphthongs. With respect to VISC, the most striking differences are that /uː/ is considerably more diphthongized in the Northern dialect and that the F2 trajectory of /əʊ/ proceeds in opposite directions in the two dialects. Cross-dialectal differences were found to be largely unaffected by the consonantal context in which the vowels were produced. The implications of the results are discussed in relation to VISC, consonantal context effects and speech perception.