Prince William - yes, that Prince William - according to Cosmopolitan magazine has gone through 3 weeks of intense spy training!
"William recently took three weeks to learn all about the UK's security and intelligence agencies. His mission included a week at M16 (aka where James Bond works—and yes, I know that James Bond isn't real, I'm just trying to give some context here!), a week at M15 (the agency that works to protect England from terrorism), and lastly a week at the Government Communications Headquarters in Cheltenham (where intelligence specialists study potential threats)."
I just don't understand the use of this for him because he is recognizable world-wide. But actually it's to help him better understand the threat level surrounding him, his family, and the UK.
"With the threat level for international terrorism in the UK set at SEVERE or above for the last five years, the Duke was keen to see first-hand the extraordinary work that staff across the Security and Intelligence Agencies do."
So no, it's not so he can become a spy but to become better equipped to handle a risky situation if one were to happen.