Pippa Middleton’s arrival at St Mark’s church in the idyllic village of Englefield for her wedding this morning put an end to weeks of speculation over a closely guarded secret – the designer of her wedding gown.

Ever since Pippa’s engagement to hedge fund manager James Matthews was announced last July, speculation has gone into overdrive over whether the youngest Middleton sister would, following Kate’s example in her 2011 royal wedding to Prince William, favor a classic design, or a contemporary style modeled by Pippa as her bridesmaid , heralding her arrival on the fashion scene.

In the event, Pippa opted for a dress by British couturier Giles Deacon, best known for his opulent red carpet gowns worn by actresses including Kate Blanchett and Sarah Jessica Parker. Deacon emerged as favorite when pictured visiting Middleton at her London home, carrying an armful of dress bags.

RTX36P33 Pippa Middleton, the sister of Britain’s Catherine, Duchess of Cambridge, arrives for her wedding to James Matthews at St Mark’s Church in Englefield, west of London, on May 20, 2017 REUTERS/Justin Tallis/Pool

With the eyes of the world on a wedding widely regarded as the society event of the year, designers and fashion labels lucky enough to win the Middleton seal of approval can see their fortunes treble overnight.

The Duchess of Cambridge’s sartorial choices can result in such a pronounced upward tick in sales, it’s been dubbed ‘the Kate effect.’ Newsweek previously reported that this royal boost may be worth as much as £1 billion to the U.K. fashion industry. The Seraphine maternity dress Kate wore in the first official portraits of Prince George sold out within hours of the publication of the pictures, while sales of Alexander McQueen rocketed 29 percent in the wake of the royal wedding, with both Kate and Pippa’s dresses designed by the firm’s creative director Sarah Burton.

It is not just the bride’s choice of dress that has the capacity to sway the fortunes of a fashion house, with the dresses worn by Kate and other high profile guests likely to attract attention. Kate wore a pink Alexander McQueen dress to the ceremony. 

RTX36P3O The Duchess of Cambridge adjusts her sisters dress at she arrives at church for her wedding. REUTERS/Kirsty Wigglesworth/Pool

Fashion commentators speculated about the fashion choice of Prince Harry’s girlfriend, actress Meghan Markle, ahead of the event, but contrary to expectation she is not believed to have attended the church service.

Deacon himself has spoken glowingly of the influence of the Middleton sisters on British fashion.

“I think they’ve both got divine style,” Deacon told Hello! last year. “They’re thoroughly modern girls promoting British brands and looking fantastic.”

In a statement released Saturday, he described himself as “thrilled” to have worked on Pippa’s wedding dress, and said it was a “privilege to show the craftsmanship that my team produces in London and a real testament to Pippa’s support of British fashion.”