Question: When was the British Labour politician Which was one of those investigated by David Shayler born? 
Sentence (from "Peter Mandelson"): Peter Benjamin Mandelson, Baron Mandelson {'1': ", '2': ", '3': ", '4': "} (born 21 October 1953) is a British Labour politician, president of international think tank Policy Network and Chairman of strategic advisory firm Global Counsel.
Relevant evidence: Yes