Swiss dividend witholding tax 35% or 15% on T212

Hey all,

With Swiss WHT being a chunky 35%, but am I right that UK has a treaty so its 15%? I have seen, when searching for an answer on here, that someone was charged the full 35%.

This would be held in an ISA on T212.

I have done a bit of searching online and Article 10 on Page 11 of this UK Government document might help: