Twin boys Yigit and Derman Evrensel, who are conjoined at the head, have been separated in pioneering surgery at London's Great Ormond Street Hospital. Channel 4 News had exclusive access to the painstaking operations, as the hospital's team used new technologies to navigate their way through separating the boys' brains. Report by Etemadil. Like us on Facebook at http://www.facebook.com/itn and follow us on Twitter at http://twitter.com/itn