Ha ha, slagging my spelling then making a mistake straight after! From what I can gather, it was Polar neck and not polo - just drifted into the same word over time. Nowt to do with playing polo, or the mints, or the ugly little VW car from the mid 70s. I always thought turtle neck was higher than a crew but shorter than a roll-neck, but this is often used to describe the high neck fold over one as well. Had a look at a few 60s Fred Perry style shirts still in the packets but they all say "Sports shirt" or "Leisure casual".