> It’s rather surprising that it’s taken this long for the OS to put its work on iOS, but the agency has at last come up with an official app.

Not so surprising if you consider that the Ordnance Survey focuses on other stuff, rather than the newest tech gadgets. Having maps on the phone is really nice for "casual" uses and navigation in towns, but this is covered quite well by the existing solutions. If I go trekking I much prefer a paper map which is larger and more robust to essentially all mishaps.