We've all seen the "saffron" Irish kilts. They're worn by the pipers in the Irish Guards and Royal Irish Rangers:





and by many civilians, pipers and nonpipers alike:



So with this all in mind, it was very interesting to read what HF McClintock has to say on the subject in Old Irish & Highland Dress:

"Saffron is a dye made from the dried stigmas of the autumn crocus (crocus sativa). The name "saffron" is from the Arabic, but the dye was known to the Greeks as Krokos whence the Latin Crocus and the Irish croch.

Though little heard of nowadays, it enjoyed a considerable reputation among the ancients and in the Middle Ages, primarily as a dye, but also as a drug, a spice, and a perfume. It was formerly much grown in England, its cultivators being called "crokers" (whence that surname) and its cultivation was kept up at Saffron Walden in Essex till as late as about 1768. In Ireland, Castle Saffron, in Co Cork is said to take its name from the quantity formerly grown there, and a pamphlet advocating its cultivation in Ireland was published by the Dublin Society in 1732...

From all this, it is beyond question both that the Irish in old days knew of saffron and that the country was capable of producing as much of it as the people cared to grow...

From experiments specially made by a competitent dyer, it was found to give a pure yellow without any tinge of brown, varying from primrose to a full buttercup shade, thus confirming exactly the colour of the tunic (leine) in De Heere's paintings...

Saffron is therefore a perfectly definite dye which was much more familiarly known in the sixteenth century than it is now; and when we find sixteenth-century writers repeatedly calling the colour of the Irish shirts "saffron" in three languages (English saffron, Latin crocotus, Irish croich), and never calling it anything else, we need very strong evidence to show that the dye was not saffron or, at any rate, a dye which produced the colour of saffron. Most of these writers indeed say explicitly that the shirts, both in Ireland and Scotland, were dyed with saffron...

I do not know what evidence there is in support of the brown shade now called "saffron" but in face of the above facts, I think it would have to be very strong."