Mikhail Gorbachev encouraged a young British boy to live a “life that makes a difference” as he told him that “the success you take will ultimately be equal to what you put in”.

Former British ambassador to Lebanon Thomas Fletcher revealed the ex- Soviet leader gave the advice in a note written during the Briton’s time as a foreign policy and Northern Ireland adviser in Downing Street.

“Over several years in 10 Downing Street I collected advice for my son, Charlie,” wrote Mr Fletcher, who worked for prime ministers Tony Blair, Gordon Brown and David Cameron between 2007 and 2011.

“I asked world leaders what they would say to themselves at 14-years-old. Mikhail Gorbachev was quite emotional as he wrote this. His translator helped too. Here it is. RIP.”

The note, which was signed “M Gorbachev” and dated June 6 2008, stated: “Dear Charlie, by the time you read this I may no longer be around, but I wish you a successful and joyful life.

“The success you take will ultimately be equal to what you put in.

“My best wishes for a life that makes a difference.”

Mr Gorbachev’s death at the age of 91 has prompted tributes from world leaders including Prime Minister Boris Johnson, who said he was “saddened” to hear of the passing at a “time of Putin’s aggression in Ukraine”.

The Russian, who brought down the Iron Curtain by introducing Glasnost and Perestroika to the Soviet Union, was famously the Soviet leader with whom Margaret Thatcher said she could do business.