Princess Di's spirit hovers over royal wedding

>>> and finally tonight, as we look at westminster abbey , three days to go until the royal wedding in london , and reports from there indicate american media way outnumber british media right in their own back yard. americans have had a long-time obsession with that family. and much of the interest in this wedding stems from the fact that the young groom, the future king of england , radiates his late mother in his face and in his smile and will forever seem that way. and then of course there's about to be a new princess as well. our report tonight from nbc 's kate snow in london .

>> reporter: it was william who ensured his mother would be a part of the big day .

>> she's not going to be around to share any of the fun and excitement, but this is my way of keeping her sort of close to it all.

>> you look at william , you see diana .

>> reporter: author christopher anderson says the two had an exceptional bond.

>> she sought his advice about much of everything. she called william her -- "my little old wise man."

>> reporter: and so the inevitable comparisons. no one expects this wedding to be as over the top as 1981 , with diana 's 25-foot train.

>> there's clearly a move afoot to try to steer away from charles and diana , to be more following the lead of the queen and prince philip , who after all have had a long and faithful marriage and have been the bedrocks of a modern monarchy and the survival of the modern monarchy.

>> reporter: and what about these two women? pick the right photos and they can look so similar, like they're playing the same part in a play, both nervous in their first on-camera interviews. but they are very different people. kate , a country girl with working-class roots.

>> how would you describe kate middleton ?

>> well balanced would be the first thing i'd say about kate middlet middleton. i think there's nothing fraught about her. there's no hidden turmoil there in the way that there was with diana .

>> reporter: and she's had more time to get used to the role. william and kate were friends first, built a relationship over many years. kate has reportedly studied videos of diana and received training from the palace on how to cope with the constant scrutiny.

>> i would love to have met her, and she's obviously -- she's an inspirational woman to look up to.

>> reporter: diana would embrace a child with aids or walk among landmines to make a point.

>> she was a darling of millions of people. i think that kate and william will be slightly more careful. they will try to present, if you like, a dream double act rather than two solo superstars like charles and diana presented themselves.

>> reporter: the memory of diana can't help but shape their future. the altar where william and kate marry is the very place he walked to behind his mother's casket.

>> hello.

>> reporter: friends say he's very protective of kate , that he learned from his mother kindness, the ability to love. william once said "not a day goes by" that he doesn't think about his mother. on his wedding day the world will be thinking about her, too. kate snow , nbc news, london .

>> and a reminder. nbc news live coverage of the royal wedding begins at 4:00 a.m . eastern time , 3:00 a.m . central, and for the west coast hardcore diehards that would be 1:00 a.m . pacific time . that's