Something light, breathable and loose. The route is walked rather than watched from a seat, in early summer, with limited shade. Heavy or structured garments become uncomfortable within about an hour.

Because where two saturated colours meet on fabric the edge can soften slightly. Wide bands hold their edges cleanly; hairline bands are the first thing to suffer. Bold blocks give the crispest result.

Front. In a dense crowd you are seen from the front and from close range, so chest placement works and fine detail is visible. The back is largely hidden, so nothing essential should sit only there.

Yes. A single-event piece can be as loud as you like. Something worn all year needs a quieter design and a cut that does not announce an occasion. Decide which before browsing.

Yes, through stadium giveaways, which covers ordering across a spread of sizes and the longer lead time larger quantities need.

Yes. Flags and other display items carry related motifs, so a group can combine worn and displayed pieces.

On an unshaded route in June it does more for comfort than any other single item. Several hours of direct sun with nowhere to retreat is the main discomfort people report.