Peter Castro on McCartney's engagement

Peter Castro says Paul McCartney's recent engagement to Heather Mills is not really a big surprise

(CNN) -- Former Beatle Paul McCartney announced his engagement to his girlfriend of three years, Heather Mills, on Thursday. Peter Castro of People magazine discussed the impending nuptials with CNN anchors Colleen McEdwards and Carol Lin on CNN Friday morning.

COLLEEN MCEDWARDS: That's a happy couple if you ever seen one. Paul McCartney, Heather Mills making it official this morning.

CAROL LIN: It is official.

MCEDWARDS: They're engaged.

LIN: Yes, it's official. Larry King, you know, in fact, was asking about ... when these two people first met. ... Heather Mills was speaking about land mines at a nonprofit -- a foundation that she ...

MORE STORIES Beatle Paul to remarry

MCEDWARDS: Yes, it's a charity that she runs for people who have had their limbs -- lost their limbs, that kind of thing. She actually had a limb amputated below the knee in a -- just a freak accident with a police motorcycle. But it's a cause she sort of took up. They met completely by accident.

LIN: Yes, and at a really good time for him. I think he had gone through a very long mourning period for his wife, Linda McCartney, who had died from breast cancer. So, we're real happy for the couple. He is 59. She is 33. You know, you take it from there. We're going to be actually talking to -- oh, we're going to go to him now.

MCEDWARDS: Yes, I think we've got him now. Peter Castro who is with People magazine and knows all about this story. He's been working on it. Peter, was this a big surprise?

PETER CASTRO: Not really. You know, Paul and Heather had been making the rounds. They were very public about their relationship and very happy. And you know, he even came on a British television show and surprised her. And it was kind of corny but sweet, gave her a kiss and professed his love on the air, which for him, was a really remarkable thing to do.

MCEDWARDS: But he is quite -- he's quite a romantic, isn't he? I mean I've heard that he is -- he's sort of a nurturer and likes to do things for others.

CASTRO: Yes, he is. And I mean, you know, he's written some of the most beautiful songs of his career for the women in his life. And he's sort of like the poster boy for monogamy. When Paul McCartney loves you, I mean it's -- you're the woman in his life forever. And he does nurture. And this is something -- I think Heather Mills a woman who he loves very much but you know he's always liked to help people. And clearly -- I mean she's an amputee victim was sort of not exactly the kind of you know, model starlet that most rockers go after. And I think he found a vulnerability in her that appealed to him very much.

LIN: Certainly, a beautiful woman. Is she anything like Linda McCartney?

CASTRO: Well, she is in that she kind of, you know, is not a celebrity in her own right, is very simple. She's also a vegetarian. I think that appealed to him enormously. They were both blonde. But I think they were also very different. And you know, he once said, "Look, Linda was the love of my life. I'll never love anyone like her. But you know, you have special kinds of love and Heather is very special to me."

LIN: What do you make of the age difference between the two?

CASTRO: Well, you know, I mean it's not a -- exactly an Anna Nicole Smith situation but it's also not unusual for aging rockers to pursue younger woman. So I mean we've seen it all before.

MCEDWARDS: Do you think he -- is he interested in her causes, though? I mean do you think now that they're engaged and as they closer to the time of the actual wedding, we'll -- the public will be seeing more of them in public, seeing them talking about their shared issues together?

CASTRO: Yes. One of the things that Paul loved about Linda was the fact that she was such an activist and she was such an activist for the rights of animals. And when Paul met Heather, actually, they were at a charity function and she was giving a speech about, you know, people who are missing limbs. And I think that appealed to him. You know, he doesn't want a ditzy -- just a -- he doesn't want an arm piece. He wants somebody with a mind and somebody who does good for other people like himself.

LIN: Great story. It's a great story and it's nice to see them so happy. Thanks so much to you.

MCEDWARDS: Thank you.

CASTRO: Thank you.