Why has the UK voice on Google Speech suddenly changed?

(I am in the UK and in the settings the voice is set to English (UK)

Last night, and for the last 2 weeks on my Nexus 4 I have been greeted with a slightly creepy sounding English male voice.
However today, on asking my phone a question I am greeted with a much more brash robotic American voice. I have tried changing the settings however this voice doesn't change.

Anyone got any ideas on whats happened or can anyone else verify that this has changed for them too?