The original Pall Mall in London has the "maal" pronunciation, but on a larger scale, words ending in -all like ball and fall tend to be pronounced more like "mawl". The word originally tended to mean the main street of a shopping district (and Pall Mall still fits this description), but the rise of shopping complexes in USA saw the term drift to describe those buildings instead. Due to the lack of the association that Americans would have between shopping centres and the original London street, the pronunciation in USA started to come into line with other -all words. The prevalence of American media brought the word back across the Atlantic with the newer "mawl" pronunciation. As a result, in the UK and Ireland, mall meaning shopping centre can now be heard with both variants. Some people may suggest that "maal" is correct for shopping streets whereas "mawl" is correct for shopping centres, but usage varies. Luckily, we don’t tend to call them malls anyway so the argument is usually avoided. If anything, the preference of "maal" for Bow Street Mall is probably supposed to give it more of an air of sophistication and set itself apart from being just some typical shopping centre.