According to Wells, words like book and cook retain the long vowel /u:/ in Northern regions of the UK (1982: 362). That is, speakers rhyme book with spook in these regions. However, this is now recessive, and in much of the UK both words are pronounced with the shorter /ʊ/ vowel.
There is, as expected, a very slight increase in book-spook rhyming in the North (18% compared to 8% in the South), but these figures are still dwarfed by the number of speakers who pronounce the two words differently, with a shorter vowel in book. The North East contains a much larger proportion of book-spook rhymers than elsewhere in England (exactly 50% of speakers); rhyming is also characteristic of our respondents from Scotland (74%) and Northern Ireland (90%).