fancy range finders haha no its called having a spotter who has a scope that displays range and wind speed/direction he calls out the these deatils and the firer simply adjusts the scope and fires , the spotter will then tell the sniper to adjust a certain way if he misses .
the british sniper would win as would any other modern sniper because simo wouldnt be able to see as far , the modern day sniper would be able to easily conceal himself and pick simo off from long range .
i often didnt have a spotter with me in my later years as the situations i was involved in simply meant my spotter was manning a machine gun , so like many experienced marksmen i could simply guess quite well a range , wind speed and direction and often was only about 700 metres tops