The T-shirt turns 100 - what's it worth?

Sarah Coles
Bob Geldof and Midge Ure
Bob Geldof and Midge Ure

T-shirts entered the world in bulk in 1913, when they were issued to Navy recruits in the US to wear under their uniforms. By 1920 they entered the dictionary, and in the 1930s they started to move beyond the world of practical cheap clothes and into fashion, music and politics.

But what is the T-shirt worth?