Go with the flow: to gentle but spellbinding effect this innovative natural history film glimpses marine life astride rising tides at Millport on the Isle of Cumbrae. Urchins, lugworm, weaver-fish and crabs are the shy-but-elegant stars coaxed onto the screen (with the assistance of Millport’s local research station) for this archetypal edition of Gaumont-British Instructional’s 1930s cinema series Secrets of Life.

• Documentary