Blue is the infantry color, formerly white. Infantry are, or were, at least, permitted to wear additional uniform distinctions like the blue disc behind the service cap and collar insignia, although the AG44 service cap is I suppose out of wear. I didn't remember they wore a blue cord, however.
One thing everyone used to wear with certain uniforms in the 1950s through the 1970s, perhaps later, was a scarf in branch colors or sometimes camouflage. It was described as "bib style," which is a fairly accurate way of putting it. They were worn usually with fatigue uniforms, which is about all that was worn overseas, except for very special occasions when class A uniforms were worn or the wool shirt and pants were worn, usually for formal guard mount or some such stuff. Mine was in cobalt blue, which meant I was.....?
Shoot low, sheriff. They're riding Shetlands!
Underneath the starry flag, civilize 'em with a Krag,
and return us to our own beloved homes!
Buy War Bonds.