There's an awful lot of ink been spilled discussing on his costume with some thinking it is for a Masque. Tom Lee wasn't posh enough for Masques. Basically it's pretty much the sort of thing any Irish aristo' might wear in hot weather. When it got colder you'd button the sleeves on your ionad, put your trews and shoes on and reach for your mantle.
As Captain of the Queen's Kern Tom commanded Irish soldiers who wore a less fancy version of his outfit. Interestingly he wrote a treatise on warfare in Ireland, he was a fearsome soldier, which I'm trying to crack down. Once I have it I can complete a blog on him.
Apparently Edmund Spenser was consumed with jealousy about Tom and loathed him.