Ever since the younger sister of Catherine the Duchess of Cambridge made headlines at her sister's wedding to Prince William in 2011 in THAT Alexander McQueen dress, the world's media and royal watchers have been impatiently waiting for Middleton junior to tie the knot.

Well, their wait is finally over. The wedding will take place on Saturday at 11.30am GMT, meaning royal watchers in eastern Australia should be toasting the marshmallows and pouring a cup of earl grey about 8.30 in the evening.

Where is the wedding?

The ceremony is taking place at the picturesque St Mark's Church in Berkshire, near where the Middleton girls grew up. The church dates back to the 12th century and was extensively restored in 1857. According to reports, the chapel holds 150 people but the entire building could hold up to 350.

The reception will take place at the estate of the bride's parents, Carole and Michael Middleton, in nearby Bucklebury.

Who is the groom?

Pippa Middleton is marrying her long-time partner James Matthews, a multi-millionaire hedge fund manager. The 41-year-old was formerly a racing car driver and in his spare time runs ultra-marathons - yes, for fun.

The pair met on the island of St Barts in 2012 and dated briefly before going their separate ways. Mr Matthews waited in the wings through Ms Middleton's relationship with Nicko Jackson and when that ended, in 2015, bam, James made his move.

After they dated for a year, Mr Matthews proposed on a romantic walk with a diamond the size of the Isle of Man.

Will the royals be attending?

You bet. Catherine and William will be guests - there has been speculation the duchess will give a reading at the ceremony - and Prince George and Princess Charlotte will be page boy and flower girl, respectively.

But the cuteness show has been overrun by headlines about whether Prince Harry's television star girlfriend, Meghan Markle, will be attending.

Despite the bride's reported "no ring no bring" policy on plus ones, Markle is reportedly on the list and was spotted arriving in London on Tuesday.

Any other high-profile guests?

Prior to his relationship with Ms Middleton, James Matthews was arguably less famous than his brother, Spencer, who starred on the UK version of The Bachelor and, prior to that, the reality series Made in Chelsea. He also penned a book about his sexploits and has reportedly beaten a steroid addiction. Safely, or sadly, his new flame, Irish model and reality TV star Vogue Williams, hasn't made the cut.

Other guests are expected to include tennis legend Roger Federer, as well as several high-profile British personalities (expect some great hats at the church). Guests have been asked to bring two outfits, a trend among brides that Ms Middleton is clearly trying to impose on her guests.

What is the bride wearing?

The bookies' favourite is Giles Deacon, who has been spotted visiting the Middleton family home in the lead-up to the big day. Other designers in the frame include Amanda Wakeley.

How much is this all costing?

Various reports have put the cost of the wedding around ??250,000 ($437,000). That's roughly 10 times the cost of the average Australian wedding, although it's hard to find reliable figures on that. Let's just settle on the fact it's costing a lot, glass marquee and all.

What's the weather doing?

The one thing no amount of money or power can control. According to BBC Weather, Saturday will start dry, before "sunshine and showers, some heavy and thundery with hail".