He played 79 Test matches and 141 one-day internationals for his country, and is widely recognised as one of the most successful all-rounders that England has ever produced.
On his quest to become a professional boxer, Flintoff said: "This is an amazing opportunity to try a sport that I love, to be tutored by a man I respect and admire and, at the age of 34, the chance to become a professional sportsman again.
"It's a huge challenge, probably the biggest I have ever undertaken, especially in such a short time-frame."
The former world featherweight champion McGuigan, 51, added: "A lot of guys feel they want to do something else. He called it quits with the cricket because he had too many injuries.
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