For those lucky enough to be invited, the big question is what to wear. The royal invitation from Queen Elizabeth commands that invited guests show up in their uniforms (if applicable), morning coats or in lounge suits. A morning coat is a traditional form of dress seen largely at weddings and at Royal Ascot. It is composed of a single-button jacket with peak lapels and tails. It is often made from light grey to dark grey fabric, and worn with a waistcoat of the same colour and trousers in a lighter shade. Prince Charles is a fan.

Since Prince William and Middleton are more modern, many might break with tradition and opt to wear a suit instead. Tailors on London's Savile Row, from storied and centuries-old houses such as Gieves & Hawkes, Davies & Son, and Kilgour to young tailors such as Richard James, Ozwald Boateng and Clive Derby of the label Rake, might be busy custom-making suits for guests.

Off the rack, the selection isn't bad, either. Dunhill's spring collection is full of suits fit for a royal wedding. Many guests are likely to show up in navy or charcoal grey. To stand out in a sea of dark-suited men, Dunhill's feather grey with subtle blue pinstripe single-breasted suit (2) should give the wearer an edge (HK$19,995). Plus, you win points for wearing a quintessentially British label.

For a thoroughly modern look, Ermenegildo Zegna has a suit made from a blend of seersucker fabric with a combination of wool, linen and silk. The Italian house calls it the Crossover Seersucker Suit (HK$28,700). This particular one is in navy (4), which makes it slightly more formal than those associated with seersucker suits.

Ralph Lauren would be a good label to wear to the wedding as well, as he is perhaps as close as you can get to having a semblance of royalty in America. There are many pieces from his Purple Label and Black Label collections to choose from, including classic three-piece suits in solid fabric or windowpane patterns to double-breasted suits with strong shoulders (1). I imagine the younger set - like Prince Andrea Casiraghi of Monaco - would be more inclined to wear Ralph Lauren Black Label.

The trick to making these suits work for a wedding, as opposed to looking like you're heading to a boardroom conference, is to stay away from coloured or striped dress shirts and fancy or aggressive ties. It is on these occasions that a starched white shirt and a solid tie make the biggest statement: quiet elegance, appropriate and dignified.

For most of us, the closest we'll get is a royal wedding viewing party, and guests might be asked to don something 'royalty worthy'. For such an event, I have my eye on a jacquard jacket with a micro pattern (3) from Gucci (HK$23,900), worn with an Ascot and monogrammed velvet slippers. Tally-ho, indeed.

Shopping list:

Dunhill, Prince's Building, Central. Tel: 2524 3663

Ermenegildo Zegna, IFC Mall, Central. Tel: 2295 0828

Gucci, The Landmark, Central. Tel: 2524 4492

Ralph Lauren, The Landmark, Central. Tel: 2869 0388