Well, Seachurch, Ludovic Kennedy may never have heard the Royal Navy called 'the Andrew', but The Oxford English Dictionary's scholars certainly have!
Here's a quote they offer from 1916: "...terms heard every day in Andrew, as the bluejacket calls the Navy." (That was published in Carry on! by someone using the pen-name Taffrail, a pretty clear naval reference.) Indeed, as far back as the 1500s a warship was often called an Andrew, so the connection is quite ancient.
Kennedy clearly wasn't really paying attention!