Help identifying white ties

[03fahnen]

Good morning to all.
I know you should know this, but what do these white ties on the shoulder pads mean?

I appreciate any information.

[David M]

I guess they are there to keep the chain in place

[Lukasz Gaszewski]

Typical of British collars. Different person, different era, same order (well, almost), same ties. Field Marshal Alan Brooke in all his glory (courtesy Defence Academy, UK - https://www.artuk.org/discover/artworks/field-marshal-viscount-alanbrooke-18831963-kg-gcb-om-gcvo-dso-42715).