Not The Saturday Prize Puzzle

NTSPP - 115 by Nina

“Lonely, Single & Broke” by Nina

On April 21st, Nina dumped her 10 of a husband, checked her diary, compiled a crossword, got 2 and made her lonely — and expensive — way from South London to her first Sloggers & Betters get-together, taking with her this commemorative puzzle to test out on those present. There she informed them that after completing the puzzle, (i) eighteen (15 + 3) squares (including the two shown) had to be highlighted, and (ii) twenty-eight further squares (30 minus the two shown), appropriately treated, so as to leave one answer suitably isolated from the others.