A flatiron is a type of coastal trading vessel designed to pass under bridges that have limited clearance. Her mast(s) are hinged or telescopic, her funnel may be hinged, and her wheelhouse may also fold flat. Flatirons were developed in the UK in the latter part of the 19th century. Most were colliers built to bring coal from North East England and South Wales to gasworks and power stations on the River Thames that were upriver from the Pool of London.