I don't think it's been mentioned but Flying Cross, the maker of the shirts, makes matching pants in Silver Tan that come with the back pocket flaps.
Their site calls them Command Pants Item #3900 Style T7-918
https://i.imgur.com/rua4XJx.jpg
Here's a screen shot of the Flying Cross site showing these pants.
https://i.imgur.com/Wry3X5n.jpg
UPDATE:
If just now (17 January) ordered the pants online from Galls.
They're not listed on their site, I had to call customer service at 800-477-7766 and custom order them. Galls calls them
Item Number ZY048.
UPDATE:
Received the pants. They are super-comfortable and fit great. Here they are, on the left, with Dickies on the right. The Dickies were picked from several colours to hand at the shop, being the colour closest to the shirt. All of the Dickies were too yellow-ochre, this pair just a tad, some far too yellow. As you can see the Flying Cross pants are more of a "pink" (like the old Officers Pinks) have the pocket flaps and wider belt loops.
https://i.imgur.com/AmEwJKj.jpg