Kate Middleton broke her own St Patrick's Day style rule, but there was a pretty good reason why

Kate Middleton maintains a style tradition every year on St Patrick's Day, but there was one year when she ditched it and wore something totally different.

• In 2015, Kate Middleton ditched her usual green outfit in favor of a grey one for the Irish celebration.
• Every other year, the Princess of Wales has worn green and it's expected she'll follow suit for 2023.
• In other royal news, an updated version of Kate Middleton's pink Boden sweater is now available with 25% off for today only.

The Prince and Princess of Wales are set to make their annual visit to the Irish Guards to mark St Patrick's Day on Friday (March 17), with stylish Kate expected to maintain her tradition of wearing green to the patriotic event.

Last year, Kate delighted royal fans in a Laura Green London Coat named The Emilia for the royal engagement to celebrate Saint Patrick's Day in Aldershot. The emerald green, military-style wool coat featured a structured dagger collar and epaulets held down with navy leather buttons and a matching wool buckle belt.

This was similar to the type of outfit Kate would usually wear on St Patrick's Day - some form of green coat dress. But back in 2015, Kate ditched her usual green look and instead wore dark grey.

Instead of her usual green ensemble, Kate wore a grey Catherine Walker coat, teamed with a brown hat from Lock & Co. It's speculated that because she was heavily pregnant with Princess Charlotte at the time, this outfit was more comfortable.

The following year, in 2016, Kate missed the St Patrick's Day parade altogether, choosing to stay at home with the young Prince George and Princess Charlotte instead.

The annual engagement was canceled in 2020 and 2021, making 2022 her first outing on St Patrick's Day since 2019. Indeed for the 2022 event, Kate wore head-to-toe green.

Kate tends to pair her green coats with matching green heels and a green hat. This is a classic style tip that Kate Middleton has stolen from the Queen, as she was also well known for her color-blocking outfits.

At many of her St Patrick's Day appearances, the Princess has opted for a military look with outfits from her go-to designers such as Alexander McQueen or Catherine Walker - she has also been known to wear high street brands like Hobbs, or another of her favorites, Emilia Wickstead.

This week, however, Kate switched her style tradition up again when she opted for an unusual navy peplum skirt suit by Erdem for the Commonwealth Day service.

The navy suit jacket was paired with what appeared to be a matching calf-length skirt, both featuring delicate white floral motifs. The jacket’s single-breasted design oozed elegance and the peplum isn’t something fans often see the Princess of Wales wearing.

We can't wait to see what the stylish Princess wears for St Patrick's Day tomorrow!