Mullingar, that can’t be inferred from the preamble. As explained in #28, there are no two-letter words in the full grid, so there must be a bar between the first and second cells of the top row. That in turn means clue A1 begins and ends in the top row. But whether it begins in the first or second column needs to be deduced.
B4 is not two synonyms backwards. It splits 1,3, and the last word of the clue is the (verbal) definition. The first word is “about”