According to Hughes et al., the pronunciation of poor with the vowel /ɔ:/ instead of traditional /ʊə/ has become increasingly common, leading to homophony with words like pour and pore (2012: 50). Hughes et al. do not offer any insight into the geographical distribution of speakers with this pronunciation, which suggests that it is quite widespread throughout the UK.
Homophony between pour and poor is clearly predominant throughout England, with the only exception being the North East, where only 34% pronounce the words the same (compare this with the 84% figure for the UK as a whole). The difference is even starker in Scotland and Northern Ireland, where the words are homophonous for only 27% and 18% of speakers, respectively.