A quick, hypothetical, question for those people who are suggesting that English-speaking (even during breaks) should be compulsory. (I think that sometimes situations are better seen from a different perspective):
Imagine you and you best English-speaking buddy travel to China for an extended holiday. After a few months you can speak enough Chinese to get by. You are running slightly low on cash and decide to do a bit of temporary work. So you look for something which isn't going to test your limited Chinese too seriously. Let's say a fast-food joint. So you ask the customers if they'd like to go large (in your best Chinese). At 1pm it's time for you and your friend to enjoy a much-needed lunch break. (Remember here that you have never spoken to your friend in Chinese, you were at school together for 7 years and spoke nothing but English). Would you, or would you not feel affronted if you were told you were not allowed to speak English? And would you be offended if someone then turned around to you and said "If you don't like this rule then go back home?" I would imagine you may have some issue to take with this type of treatment.
But... crucially... the people we are expecting to drop all that comes naturally to them -their mother tongue- are not in England on holiday. They are here to earn a living. To get by the best they can (on abysmal McDonalds salaries). Please don't tell me that there is any reason why they should be forced to speak English whilst they are taking a break at work.
On a slightly different (yet relevant) note, when I travelled around Europe this summer, I can unequivocally say that the British are the worst tourists imaginable when it comes to the issue of language. When speaking to a French person, a German or an Italian I saw British people assume that they would be able to speak in English and be understood. In one month I saw this happen numerous times. In England I am yet to see a French person arrive with such a blasé attitude as to expect to be understood when he speaks French. It just doesn't happen. Europeans make much more effort when it comes to this question.
Sorry for the length of this post, but I hope it explains my disgust at people who say (nay grunt) things like "Speak English or piss off back home".