Heritage Open Day: Come celebrate Marple's rich heritage and immerse yourself in a range of free activities! From canoeing, to heritage walks, historic boat display, lock demonstrations, family crafts and much more! There really is something here for everybody! Completed in 1804, Marple Lock Flight consists of 16 canal locks and is one of the steepest flights in Britain. No longer needed for commercial use, the locks became impassable by the 1960's. But with huge thanks to many dedicated canal enthusiasts, the flight was saved, restored and re-opened in 1974.