https://www.theguardian.com/uk/2013/jun/21/gchq-cables-secret-world-communications-nsa
" a total of 850,000 NSA employees and US private contractors with top secret clearance had access to GCHQ databases."
https://www.channel4.com/news/by/tom-clarke/blogs/nsa-spying-bude-gchq-edward-snowden-prism-seaside-rudyard-kipling
"what has come as a surprise are the revelations about how GCHQ, with its US partner the NSA, may have the ability to capture and store all of the data traffic coming across undersea cables crossing the Atlantic through a programme called Tempora."