Buttoned up in a black coat and her brunette locks down, the 29-year-old went in for a smooch from the stockbroker, 35, as they were about to leave sitting in the backseat of a car. Jackson also wore a matching black suit for the outing.
Incidentally, Middleton hinted at becoming a future bride in her latest column published in The Telegraph U.K. newspaper Saturday morning. In the article -- titled Sport and Social -- Middleton details on how to pick the best bouquets for flower arrangements.
"Much like buying a Christmas tree at a nursery, the picking and pruning are part of the enjoyment," she wrote. "Next stop, a flower-arranging course. Maybe I'll be a DIY bride?"
Could the world famous royal bridesmaid be hinting at an upcoming wedding? Reports claimed in early September that the pair were engaged, but as sources revealed to Us Weekly, nuptials just aren't in the cards -- yet.
Middleton previously dated England cricketer and financier Alex Loudon from 2010 to 2011 and briefly dated university friend George Percy in 2012.