outrider

noun3

1. •
   A guide or escort, especially one who rides in advance.

   • Then they went from farmhouse to farmhouse, two little girls walking at the head of the procession as bridesmaids, and six or eight outriders galloping ahead on hobby-horses to announce their coming. — 1890
2. •
   (figurative) A forerunner.

   • The Winchester MP is something of an outrider for a new project now: moving his party into the space vacated by the Conservative shift to the right under Iain Duncan Smith. — 2001
3. •
   One who rides out on horseback to inspect a ranch etc.