I have not seen the commercial yet, but I helped with one of the Red Robin commercials (vendor) with the man trying to entice the 'Coldstream Guard' into breaking his code of silence by saying "Yum" in front of Buckingham Palace.
Since it was MODERN British army, I offered a High end L85 airsoft with the correct sling and rainguard for the Coldstream guard. The Art director's assistant looked at me like I was a moron.
No, the director WON'T like this, she said. I countered that it was CORRECT. I pointed out that she should look at the movie "Patriot Games" or see any current photos of the Palace guards to see what weapons they carry. For ceremonial purposes, I can see them holding 'prettied up' versions of the Enfield. So I offered a Lee Enfield with a white parade strap.
A few days later, I got the word that one of the Art director assistants used Her grandfather's M1 Garand, since
"that is what they used" .........
So I'm sitting there and saying "Hey, show me ONE photograph where a British Army officer or enlisted man is holding an M1 Garand".
After the gig is over and I lost the argument, the girl shows me a Black and white photo and says "Here, see you were wrong"..... the photo is of an AMERICAN soldier in 1939 (before the war) with a doughboy helmet, an M1903 Springfield rifle and cold weather greatcoat and 10 pocket ammo belt. It's not a British soldier at all........
So if you see a Red Robin television commercial where the Brit is carrying an American M1 Garand rifle, that could be the one I tried to offer advice on. I've heard someone say they saw it. I haven't though, so I don't know if they used a Garand or not.