He and another former policeman are considering forming a company providing personal safety and communications skills.
With Prince Charles and his wife Camilla visiting New Zealand, the Advocate asked Mr Evans what was involved in keeping royals safe.
He hadn't had much to do with Charles, other than when the prince called to see his mother.
"Whenever Charles visited the whole mood lifted. The Queen's staff liked the prince because he was always good-natured and jovial," Mr Evans said.
His bodyguard work began after a man got into the Queen's bedroom after breaking in to Buckingham Palace in London in 1982.
Another major incident he missed was the fire which destroyed much of Windsor Castle in 1992.
Security was tightened after the intruder and fire, with the Queen so concerned about fire safety she would sometimes ask her guards to check alarms were on before she turned in at night.
Mr Evans said the Queen was "a nice lady" and he felt relaxed with her. While she would sometimes chat, their conversation was very formal.
"She called me 'officer' and I called her 'Your Majesty'."
All royal visits overseas - such as when the Queen visited New Zealand in 2002 - were "intelligence-led", with royal bodyguards arriving long before the monarch to tee up security with local police.
Back in Britain, the guards dealt with protesters like Dads' Rights for Justice, who dressed in Superman costumes and chained themselves to castle gates. They also made sure that people who set off alarms when they climbed fences didn't reach the Queen.
Mr Evans won't discuss anything personal about the royals because he was in a "private position of trust".
But, while mild in manner, his role included forceful strength if required. He is trained in unarmed combat, carried a Glock 9mm pistol and is an expert with a submachine gun.
