“Potter” producer David Heyman was thinking of that when he told Radcliffe that there was no way that three “strangers” could deliver the final lines of the three main characters right before the final fade to black.

“After all we have been through with these characters, the way that a generation has grown up with them, they need to be the ones on screen when it’s time to bring it to a close,” said Heyman, who was a key decision-maker back when Radcliffe and his costars were first cast in their roles back in 2000. “There’s an expectation — even if it is not articulated — that they need to be on the screen when it’s coming to an end.”

“The thing we didn’t want was for it to be distracting and I think we figured it out,” Radcliffe said. “We did it with prosthetics, in the end, and I’m sure there will be little bits of visual effects for retouching on those moments when we do a close-up… when you have the prosthetic on for a long time, it’s hard to maintain it, that illusion, and with close-ups you need to fix it up. It’s also a challenge to make someone who is 19 or 20 — an age where their face is still changing — and make them a fully grown adult. I think they looked fantastic though and, if I do say so, particularly mine. Mine looked pretty dead on. That’s me in the future I think.”

“Rupert looked like he was about 75 years old with the triple chin and the belly, he looked like he had really lived as a lush,” Heyman said. “We knew we needed to rework the makeup. There was another problem, too, shooting at the train station proved quite challenging for some of the younger kids who played the children of Harry, Ron and Hermione. It was really noisy every few minutes a train from Liverpool would pull in on one of the other tracks. We only had our one track closed.”

The makeup team for “Deathly Hallows” was led by Nick Dudman and, to Heyman, the second shot on the “age-up” work was a home run.

“It made all the difference in the world,” Heyman said. “We got what we were looking for. There was a challenge in the performance for the young actors. I know Emma talked about her approach was to think of her young siblings — her father has remarried and she has a new family — and how being with them was her way to get into the head of a parent going off to school. It wasn’t easy for them.”

“We should have thought to film it last in the first place,” Heyman said Wednesday. “It created a reality of sorts to the feelings in the scene and in the air. And I think now we’ve heard from the rest of the world that it worked. In the end, we used some shots from King’s Cross, too, to make a hybrid. There was a little bit of CG as well. The combination is subtle, which it needed to be.”

“It was something very strange and affecting,” Heyman said. “I was really pleased because I thought there was a real tenderness about the last scene, a feeling of closure and the cycles of life. There’s a new beginning and there’s an ending. There are different sorts of adventures for these actors and for all of us. But we made it to the train station together.”