The British town of Windsor will be crawling with security and police tomorrow, as crowds cheer for the Royal newlyweds.

More than 100,000 people are expected to be there for the marriage of Prince Harry and Meghan Markle.

SAS-trained Ken Wharfe has held various security roles with the Royals.

The former head of security for Prince Charles and bodyguard to Princess Diana, says there's always going to be a risk when members of the royal family travel in an open carriage.

Wharfe told Larry Williams professionals have been securing the area for weeks.

"Every property would have been visited, every homeowner would have been spoken to and of course you can expect a fairly high presence of police snipers on the rooftops etcetera and the policing of the crowd."

He says since the wedding of Prince William and Catherine a lot has happened internationally, including a rise in terrorism.

But he is confident in the measures put in place saying police and security services will have been planning security since the engagement was announced.

"There's a lot more work to be done, but I am pretty confident that with their expertise the country and the world can expect a happy day."

LISTEN ABOVE AS KEN WHARFE SPEAKS TO LARRY WILLIAMS