A bit of background for you. As you know, a Guardsman has no insignia on his tunic.
A Lance Corporal in the Guards has 2 white stripes on his sleeve. Everywhere else in the British Army, a Lance Corporal has a single stripe. It's said that Queen Victoria declared that no man with a single stripe on his tunic would guard her, so the Guards Lance Corporals got an extra stripe.
Of course, this posed a bit of a problem, because 2 stripes normally means a Corporal. Three stripes mean a Sergeant. So the Guards instituted the rank of Lance Sergeant and gave him 3 white stripes, like the one Graf has.
A Guards Sergeant has 3 GOLD stripes on his sleeve. Colour Sergeants have an actual picture of a standard (colour)... and the Regimental Sergeant Major has a huge Royal coat-of-arms on his sleeve!