The Glen and Prince of Wales checks are both woven twill plaid patterns consisting of large and small checks.
“Glen” actually refers to the Glen Urquhart valley in Scotland where the checked pattern of wool was first used back in the 19th century; a mixture of checks, the Glen plaid (or Glen Urquhart plaid) has become a fashionable choice for a men’s suit. It retains an air of classic elegance, and the pattern is small enough to work well with most accessories while softening the formality of the suit.
The Glen plaid works well in tones of grey, with the checks in lighter shades currently amongst the most popular.
The Prince of Wales check is a popular variant. It is a combination of red, cream, black and grey, with the regularity of the standard Glen check alleviated by including a larger and more open windowpane check on top of the pattern. As with many sartorial matters it gets its name from the late Duke of Windsor; he popularized the style in the 1930s when he was still the Prince of Wales.