Kate Middleton in Jane Taylor hat

When it comes to events in the Royal calendar, for Kate Middleton and co. a coordinating hat is a fashion essential, and the anniversary celebration of the Queen's Coronation at Westminster Abbey was no exception.

Giving us a tried and tested lesson in topping off a formal look, the Duchess of Cambridge opted for the same Jane Taylor hat she wore at last year's Jubilee lunch. Like in 2012, the fan-detail headpiece was carefully coordinated to a lace dress, though this time she swapped Alexander McQueen for a pregnancy-appropriate empire dress by Jenny Packham.

The Queen

Equally expertly coordinated was leading lady of the day, The Queen. With decades of practice, it's no surprise HRH was elegantly kitted out with a wide-brim hat in the same fabric as her jacquard dress coat. For extra points, it had faux roses attached under brim in a matching shade to her brooch.

Princess Beatrice

WEDDING GUEST OUTFITS

More experimental in the millinery stakes was Princess Beatrice who made a controversial choice of hat at the Royal wedding, but clearly wasn't perturbed as she matched her amethyst-hued outfit with a feathered fascinator by Sarah Cant.

SUMMER ACCESSORIES

Zara Phillips

Zara Phillips was the most fashion-foward guest of the day with her choice of ornate black Karen Henriksen hat, matched with graphic print shift.

WATCH: KATE MIDDLETON'S BEST BEAUTY LOOKS...