Gilbert had led the final warm-up event ahead of Sunday's prestigious Tour of Flanders since taking the opening stage. The 34-year-old Quick Step Floors rider is targeting the cobbled classics this season as he bids to win Sunday's race known as the "Monument" for the first time.
"There is no better preparation for the Tour of Flanders," declared the Belgian champion, who finished 38sec clear of Matthias Brandle in the overall standings.
The closing 14.2 kilometre race against the clock was dominated by Durbridge after the morning's third stage, also in De Panne, Belgium, was annexed by Marcel Kittel.
The German beat off Alexander Kristoff, who took third overall, and Sacha Modolo in a sprint.
