"When Steve Jobs died last week, there was a huge outcry, and that was very moving and justified. But Dennis had a bigger effect, and the public doesn't even know who he is,"

Unix and C's direct and spiritual descendants cannot be counted, but include Linux, Android, Mac OS, iOS, JavaScript, C++, the genius of the internet and a world full of developers. Likewise, legal restrictions on how Bell Labs and its parent, AT&T, could commercially exploit software — an antitrust ruling prevented standard licensing — meant that the ideas and, often, the actual code underlying Unix and C became a de facto open system.

Ritchie had the lifestyle and habits to match his position as an early guru of IT. Long-haired and bearded, and famously more owl than lark, he started work at midday in his industry-standard chaotic office, emerging late in the evening to go home and carry on working through to the small hours at the end of a leased line connected to the Bell Labs computers.

In later life, having become a manager, he could sometimes be seen in the wild before lunchtime, if meetings demanded it. His life and work were entirely intertwined; a man celebrated for his gentle wit and gentle ways, nothing about him could be considered separate from his lifelong fascination with computing.