The techniques of documentary film-making are unbeatable when it comes to explaining new procedures or how something works, or putting a difficult case in a compelling way.

A National Health Service trust in south west England wanted to rebuild its hospital under the UK government’s Private Finance Initiative. It was a controversial scheme, and the public didn’t see why a 1970s tower block needed to be demolished. But a video showing doctors and nurses at work, explaining and showing how cramped and inconvenient they found their working conditions, helped them see the arguments for change.

Tony Coll has also made very factual technical programmes on subjects as varied as the maintenance of train gear boxes, how to keep a pub cellar, and how to apply new building regulations in the defence industry. When a non-professional presenter is involved, filming can be combined with coaching on how to give the best on-camera performance.