Even if you can tell your Silurian greywacke from your Mourne granite, this epic dam building project in Northern Ireland is still a mighty feat. John Laing & Son were the company behind some of the biggest construction projects of the 20th century, from motorways and power stations to cathedrals. Luckily for civil engineering fans, they were keen to document and promote their work on film through a well-resourced unit in their PR department.

This two and a half year project high in the Mourne Mountains was typical of the remote civil engineering projects John Laing & Son undertook. Necessary, perhaps, but an incursion into nature that rarely runs smoothly. Unsurprisingly, the film glosses over problems that occurred when a misjudgement of the true level of the bedrock caused the first concrete pour to sink. But the dam still stands, and the reservoir remains an important part of the water supply to the area.