"The Dark Man", on
YouTubeThe climax was filmed at Dungeness and shows the Appledore line and the Romney, Hythe & Dymchurch Railway at Dungeness c1950.
Then & nowIMDB which points out some of the plot holes, not least why did the bad guy hang around to try to eliminate a witness who'd glimpsed him only from a distance? Exchange of pistol shots at impossible distances. Improbable use of armed soldiers firing at the fugitive.
Features the very first Dr Who and character actor Sam Kydd.