Sergeant Jonathan Westrupp has no recollection of diving head first through the glass of a second-storey bathroom window during an armed siege in April. Moments beforehand, however, he knows he made a calculated decision that it was the best option to get away from a wanted man who had just shot and killed a police dog in the hallway of the Porirua house. Ellen Brook reports.

We live in a world where the tasks and activities necessary to achieve goals are narrowly defined, broken down into their component parts – it’s called specialisation, and it makes sense.