Odd lightning conductor at Urquhart Castle

The big tower at Urquhart Castle on Loch Ness had an interesting lightning conductor. A little Internet research suggests that some of the things I thought I knew about lightning conductors might be myths, so more research needed. I know that a sharp point concentrates the charge and makes for a bigger electric field strength at the tip. With a Van de Graaff generator, you also get a noticeable electric wind being pushed away from the tip. The concentrating of the electric field means that you are more likely to reach breakdown field strength there, making a strike more likely. I have read that there is some controversy over whether ball shapes might be better. This design seems to be hedging its bets. Maybe 3 spikes gives 3 chances for a reaching of the breakdown field strength. I saw one uncorroborated suggestion that it stops a strike leaping from the spike to the roof.