Series 3 began in true style with the debut of Lady Mary's sumptuous wedding gown. Downton's most expensive design set production back £4,000 and came with Swarovski crystal beads, tiny pearl buttons and an ethereal silver lace veil.

All the vintage inspiration a wannabe bride could want.

Post-nuptials and the style wins continued.

Little wonder Lady Mary led the way: her low-waisted dress is a classic example of the fashion risks young women were starting to take in the 1920s.

Gone were the fussy embellishments of Edwardian times, replaced by simpler and more flattering outlines.

And the silk parasol was a must-have accessory.

Lady Edith was quick to catch on, ditching her corset in favour of the flapper look.

The devil here is in the details - intricate embroidery, pearl strands and wide-brimmed hats all evolved into key trends in the 20s, along with the daringly stylish bob haircut.

As the Art Deco period kicked in, it was very much out with the old as women swapped heavy skirts and frills for lighter, more flexible dresses that allowed more movement.

Lady Rosamund's outfit here is typical of this transition, with emphasis on lace, pearls and pleats for decoration rather than the dress itself.

Seen in full-length, we can appreciate how far Downton fashion has developed since the show began in 1912.

Note the rising hems (both Lady Mary and her sister are showing their ankles, an unthinkable act just 10 years before) and the lowering waist bands, plus an injection of seasonal colour and Lady Edith's fabulous cloche hat.

Even the bed wear was glamorous.

These glorious kimono-style dressing gowns put our scruffy towelling robes to shame (and make us re-assess the recent pyjamas trend in a new, more favourable light).

The Crawley sisters were way ahead of their time with these mixed print paisley blouses.

Combining heritage and glamour with a subtle demureness, they wouldn't go amiss on SS13 catwalks.

Aah, garden party hats. Wide-brimmed and beautiful, they were a triumph of 1920s tailoring and went perfectly with a pair of gauntlet-length gloves.

Evening gloves were a central feature of Roaring Twenties style, encapsulating both the prosperity and artistic flair of the era.

Around this time Coco Chanel created a storm by pairing long strands of pearls with tweed, so it's perhaps little surprise that the Downton women were quick to snap up the trend with their own bead pendants.

Lady Mary paired hers with a wavy bob and wine-coloured gown for the ultimate cocktail hour apparel.

Lady Edith made a statement of hers, completing the look with a curly bob (think Clara Bow), gloves and a golden bead cuff.

Even the usually individual Lady Sybil got in on the ubiquitous trend, with beads adding the finishing touch to her stylish maternity two-piece.

Smaller details also played a key role in conjuring up an air of 1920s decadence, including curls, decorative hems and dainty jewellery bands.

Glamour granny from the States Martha Levinson took the 1920s influence in Downton up a notch with bold, brassy adornments including this emerald green necklace and peacock feather headwear.

Her entrance to Downton was hardly understated. With lavish furs, matching gold-print coat and fascinator and statement bee-sting lips, Martha made her style impact felt from the out.

Lady Mary was low-key in comparison, although her Art Deco-style hat and embellished jacket combo was the epitome of a modern 1920s woman.

Her maid Anna Bates was also a model of discreet tailoring, opting for neutral colours and classic design.

But it wasn't just women undergoing a style revolution in the early 20s: men's fashion also changed quite radically.

Pictured alongside his beloved Anna (with a risqué cinched waist), Bates also plumped for a slimmer waist and wider leg than ever seen before, with a nifty Capone-esque hat.

Lord Grantham was dashing as ever in a tux and waistcoat.

Sartorial kudos must also go to Carson: while he didn't necessarily pick up on the rapidly changing 20s trends, he looked flawless as ever in a tie, jacket and slicked back hair.