In researching this story online, I learned the reunion took place in 1974. The gentleman who walks up at the end is George Adamson. The two men who raised Christian had contacted George because he had devoted his life to working with lions and they felt Christian would have better success if George assisted. Perhaps you will remember this wildlife conservationist if I mention the movie "Born Free" which tells the story of George and his wife Joy raising 3 lion cubs.
John and Ace had made sporadic trips to Kenya to learn how Christian was doing in his relocation but mainly had to be content learning about it from a long distance. Christian and his parents were born in captivity, so this was no easy feat to introduce a captive born lion into the wild. When John and Ace decided to make one last trip to Kora in hopes of seeing Christian and saying goodbye, Adamson wrote them to say it would probably be a wasted mission as no one had see Christian for at least 9 months. John and Ace insisted they were going to come there anyway just on the off chance they could locate him.
Even George was surprised when Christian and his pride showed up right outside of camp the night before the British born lion's two former "roommates" arrived. Isn't it amazing how a lion who had not been seen in months shows up at the exact spot where John and Ace were going to be the very next day. Now "That's Something!"