Telecom company Cable and Wireless, which is now owned by Vodafone, worked intimately with GCHQ in 2010 and even handed over information from foreign rival firm.
http://www.channel4.com/news/spy-cable-revealed-how-telecoms-firm-worked-with-gchq
Here the former GCHQ head storms off of a live interview regarding the story.
https://www.youtube.com/watch?v=olcYdzny_vg