Why Rory McIlroy's Caddie Is Wearing Number 1 On His White Masters Boilersuit

One of many long-standing traditions of The Masters is the distinctive white boilersuits and green hats worn by the caddies.

That is a practice that has been in place since the 1940s, when tournament co-founder Clifford Roberts first suggested it.

For many years, caddies at the tournament were provided by Augusta National, where they would wear the uniform.

That changed in 1983, when the Masters Tournament Committee gave the go-ahead for players to use their own caddies, but the boilersuits remained, hence why they’re still used to this day.

Fans may have noticed that, on the left breast pocket of each of the caddies’ uniforms, there is a green number. This year, Rory McIlroy’s long-term looper and friend, Harry Diamond, has the number one. But why is that?

A year ago, when McIlroy completed the career Grand Slam, he also had Diamond to assist him.

However, back then, the number on his boilersuit was 81. The number is allocated based on the order the players check in to register during Masters week.

That doesn’t mean Diamond’s boilersuit has the number 1 on it this year because McIlroy was the first to check in, though.

The reason Diamond has been allocated the number 1 is that McIlroy is the defending champion. This is another Masters tradition, where the previous winner’s caddie is assigned number one regardless of the order in which players check in.

Similarly, in 2025, the defending champion was Scottie Scheffler. As a result, on his way to placing fourth, his caddie, Ted Scott, had the number one on his uniform throughout the week.

But why do Masters caddies need numbers at all?

In most other tournaments, the golfer a caddie is working for is identifiable by the player’s surname on the back of their bib.

As with many things, though, Augusta National does things a little differently. Instead, the numbers on the caddies’ uniforms are entered beside the relevant player on the groupings sheets.

Returning to McIlroy, he and Diamond are currently plotting a way for him to become only the fourth back-to-back winner of the event.

After the opening round, Diamond seemed likelier than most to be sporting the number 1 again in 12 months, with McIlroy finishing the day as co-leader with Sam Burns on five under.