I'm using an English(UK) keyboard, I set it up so when installing Ubuntu. English(US) appears as an alternative layout in the Text Entry settings window. Every few days the layout configuration will switch to the English(US) layout.
I can revert back to the UK configuration either by removing the US layout (and then adding it back a few days later when the layout or changes again) or by toggling back and forth via the unity icon (appears as En1 styled like a chemical element).
I'd like the keyboard layout to remain as English(UK) on a permanent basis and would appreciate if anyone could explain the cause and solution to this problem.