flagman

plural flagmen

1. A man who carries a flag, especially one used for signalling.

   At the approach to Southampton Terminus, double track branches off to the left, runs alongside the platforms and then cuts across Canute Road on an open crossing under the protection of a flagman.

   1959 February, G. Freeman Allen, “Southampton—Gateway to the Ocean”, in Trains Illustrated, page 88

2. A man who raises a flag.

   "The Bands played the National Anthem and the Royal Standard was cracked by the Flagman and flown beside the clocktower at the top of the Horse Guards building."https://www.army.mod.uk/news/splendour-and-precision-from-the-british-army-for-the-japanese-state-visit/