I follow the use of English in Switzerland more than in other parts of the world because my school is made up of a large percentage of Swiss students. Most of them come to San Diego to prepare for the Cambridge Certificate Exams.
On my first trip to Switzerland in 2001, I went with the expectation that the people there could speak at least two of their four national languages (German, French, Italian, Romansh) and that since I knew some French, I could rely on that more than on German. I didn't expect people to prefer to use English. Contrary to my image of a country where people moved freely from region to region, easily slipping into French in Geneva, Italian in Lugano, and German in Zurich, there were strong feelings against German-speakers in the French or Italian part, and against Italian- or French-speakers in the German part. So, apparently, the way this small country functions with four distinct national languages is by strong regional linguistic separation. In addition, with the recent introduction of English into the public school system, English is becoming the neutral lingua franca of Switzerland. That is, most German speakers would rather speak English than French in Geneva, and French Swiss would rather speak English than German in Zurich.
Naturally, I am not the first to make this observation, and I've often queried my students about this phenomenon. Their responses vary. For example, I have encountered Swiss school teachers who were rather irritated or indignant that they had to pass an advanced level Cambridge exam in order to secure or hang on to their teaching positions in Switzerland, even though English is not one of the country's national languages nor is there any deep historical connection to an English-speaking country. (But see an account of the English love of Swiss). On the other hand, many young Swiss German students are happy that they had an opportunity to study English early in their education. Few German-speakers enjoy studying French, especially since they 'dislike the sound of it.' Likewise, the French and Italians claim that German is a harsh-sounding language that is difficult for them to pronounce.
The following are some online references which you might want to peruse. The first is an essay by Duermueller entitled "English in Switzerland: From Foreign Language to Lingua Franca?"From a different perspective, there is an abstract by Christof Demont-Heinrich, "Language and National Identity in the Era of Globalization: The Case of English in Switzerland." For a historical perspective, Duermueller also wrote an article about 20 years ago based on a survey of roughly 5,000 Swiss military recruits, exploring their attitudes toward learning English.
Romansh, which is a nationally recognized language of Switzerland, now appears less important than English. In fact, the canton of Zurich broke tradition when it made the change from French to English as 'the first foreign language' for its school-age children. Swissinfo.com comments here on the importance of English - the Fifth language of Switzerland? Finally, here is some commentary in French and German about English in Swiss schools.