With regard to the sash, I found that the sash has a tassel at each end and knotted to form a single tassel. It is possible the 'loop' I am seeing is actually part of the knot.
I also found this which may be of interest to others:
talesfromthesupplydepot.blog/2016/08/24/sergeants-sash/
One of the oldest items of uniform in the British Army is the scarlet sash worn over the shoulder by NCOs. Amongst a variety of origin stories one of the most common is that the sash was originally worn by pikemen, they would wipe their hands on it to remove the blood of horses they impaled on their pikes so they did not lose grip of their weapon and it became a blood red colour. The longer they served and the higher the rank, the more their sash became a deep red colour and it became a badge of honour and rank. How true this story was is hard to establish, but it is true that the sash has been in use for many centuries.
and a slightly different viewpoint here:
www.britishbadgeforum.com/forums/showthread.php?t=25084&page=2
It is a very old tradition in the British and by extension Empire/Commonwealth military that both officers and sergeants wear a red sash and yes, originally it was only worn with scarlet, white or KD best uniforms and not in blue or khaki serge or other working undress. The purpose was two fold, it made the officers and sergeants distinctive in the smoke and fog of war, but it also acted as litter when wounded and (in the case of officers) as a shroud. The officers sash was made of silken netting that expanded but the sergeants was woven worsted and originally with a band of facing colour through the centre. By 1881 all were scarlet and the only change was moving the sash to and fro between shoulder and waist at various periods of time. When khaki SD was first introduced the sash was not worn because it was an undress field uniform, but in an effort to dress up the drab uniform for parade in the 1920s permission was granted for the sash to be worn again. Officers however, continued only to wear the sash with best uniform and that is still the case today, when it is only worn with No1 Dress Ceremonial.