I suppose to be chemically correct, I should refer to “high visibilty jackets”. A caller to the local radio station described how he had seen about ten men wearing said jackets on a motorway bridge he had just passed under. They had clipboards – half were looking at north-bound traffic, half at southbound. The caller described this as “an amazing sight”. Mmm. I am not sure if Wordsworth would have got far with “A host of men in golden jackets…” I guess we all drive to a different muse.