The plot of the film Plots with a View takes place in Wales, in the fictional town of Wrottin Powys. Brenda Blethyn plays the main character, who speaks English with a Welsh-like non-rhotic accent.I haven’t seen the film, so can’t comment directly. In my Accents of English book I said (p. 381) that in south Wales
Having watched the film a couple of times, I noticed that, in addition to the pronunciation of [ø:] in NURSE words, Brenda Blethyn pronounces NEAR words (here, beard) with [y:], with visible lip-rounding. On one occasion she also pronounces the word 'girl' as [gy:l] instead of [gø:l]. I should perhaps mention that her pronunciation of GOOSE words in this film is a relatively retracted [u:]. (Sorry I can't provide a link to a video that shows all this, you'll have to trust me.)
In NEAR words there is usually /jɜː/, so that beer /bjɜː/ can be said to rhyme with fur /fɜː/ as well as with fear /fjɜː/, while year, ear, and (/h/-dropped) here are all identical as /jɜː/. Some speakers, though use a disyllabic sequence /iːə/, thus beer /ˈbiːə/ etc.,, and in the environment _rV simple /iː/ is usual, thus period /ˈpiːriːəd/…We know that NURSE is often rounded in southeast Wales, “giving the effect of a centralized raised [œː] or lowered [øː]” (p. 381), with an “auditorily unusual quality” (p. 383). So what one would expect for here is something like (h)jøː. If Brenda Blethyn really says (h)yː, this could be seen as a kind of coalescence in which two segments, j and øː, are collapsed into a single segment yː that shares the features of both.
Roy has another theory.
Suppose that Brenda Blethyn normally pronounces NURSE as a slightly advanced schwa, and NEAR with a slightly advanced high-central-unrounded monophthong (as many speakers of Estuary English do). These two vowels may actually form a vertical series for her. Then, as part of the effort to sound Welsh, she pronounces this series as front-rounded, thus correctly pronouncing [ø:] in NURSE but incorrectly pronouncing [y:] in NEAR.Ingenious! Do we buy this?
(Blethyn is her married name. She was born Brenda Bottle in Ramsgate, Kent, and as far as I know has no Welsh connection beyond the surname of her ex-husband, which she retains as her professional name.)