The spread collar dress shirt was made popular by Prince Edward, the former Prince of Wales who eventually abdicated his throne and became the duke of Windsor, as he wore them with his signature tie knot (Aptly named the Windsor knot). When he combined his spread collar dress shirts (more commonly known as the British cut away collar), with his glenurquhart plaid (more commonly known as the Prince of Whales check) and his bench made shoes, he created the quintessential British look and became a style and fashion icon for generation.
Now that business casual is seemingly on its last legs, the return of the well dressed man is ushering back the spread collar. Wearing it the right way can go a long way to achieving the classic British look:
Choose the right spread. Most people do not know that there are varying degrees of spread and choosing the right one can help accentuate your face and give a slimming effect. If you have a pointy or heart shaped face, a classic British cut away spread will work best. This is characterized by its almost horizontal collar and goes well with the full Windsor knot. If your face is on the rounder side choose a modified spread. Not quite as wide spread as the cut away version, this collar will be better when paired with the half Windsor knot.
Choose the right collar size. Make sure that the collar is proportionate to the rest of your clothes. If you like to wear a traditional suit with wide lapels and wear a standard tie opt for a collar with 3″ points to balance out the look. If its a MOD look you are going after, pair your slim lapels and 1.5″ ties with the appropriate 2″ point collar.
Mind the fabric. Look for fine English popeline in the 2 ply variety. Many custom shirts deal exclusively in this for their spread collar shirts because of its body and durability. Avoid heavy Oxfords or nail heads as it tends to look bulky and can be hard to wear with such a wide spread.
Wear it always with a tie. This collar looks its best when it is worn buttoned and with a tie. The spread does not allow it to stand tall on its own so it has a tendency to look sloppy otherwise.