Practice Makes Perfect for Kate Middleton? Her Latest Wedding Walkthrough as Harry Makes Girls Swoon

Bride-to-be has yet another rehearsal before her big day, but it's William's younger bro who steals the spotlight

Apparently Kate Middleton really doesn't want to slip up on her big day.

For the second time in as many days, the princess-to-be surprised onlookers as she arrived at Westminster Abbey today with mom Carole, her bridesmaids and her future (in less than 24 hours!) brother-in-law Prince Harry for yet one more pre-wedding walkthrough before she swaps vows with Prince William.

And while the country's future queen caused some crowd chaos, turns out it was the ginger-haired Harry who made everyone go completely mental.

What did the royal rock star do to make the girls scream?

"We were literally jumping up and down and screaming," she said. "We got a good, proper view of him waving, he winked directly at us, of course."

Another committed wedding watcher, Susannah Brockman, said she also got a bit swoony over the bachelor prince when she saw the wave.

"We embarassed ourselves completely out here," she laughed. "It was awful."

William wasn't in attendance for today's run-through—which featured a pretty Kate arriving at the church in a black-and-white dress and black wedge shoes with her bridal party. She was escorted by police through the streets to the Abbey, which is now lined with spotless, huge Union Jack flags and freshly cut gardens all around the building and on the adjacent streets.

And how the crowds have grown!

Emma Corby came celebrate, staking out a spot on the sidewalk after hearing that Kate had swung by earlier.

"I wanted to come see this, everyone is so happy and smiling," she said. "I love that Kate was just a proper school girl and she's going to be queen now."

Unfortunately, not everyone gathered outside was close enough to catch a glimpse of Harry, or of their queen-to-be.

"What I saw was a lot of cars and a lot of police cars and a lot of action all of a sudden," Sarah Barnard, who is camped in a tent outside the Abbey, told us. "Then it was suddenly crazy when a Land Rover pulled up and everybody went crazy. The police cars were surrounding her vehicle."

Barnard said that was just a small indication of what the full wedding fever will be like tomorrow.

"The atmosphere in itself is amazing here," she told us. "People are excited to see them, They are a very good match."