Startups are an incredibly contentious thing among early modern re-enactors. So, what is a startup – good question – because even in the sixteenth and seventeenth centuries they do not appear to be certain of anything beyond the fact that they are footwear.
They are mentioned in 1551-2, Edward VI has, an Act against Regrators and Ingrossers of Tanned Leather. Chapter 15, section 5. “no Person or Persons shall ship … over the Seas as Merchandise to be sold or exchanged there any Shoes, Boots, Buskins, Stertups or Slippers.”
First appearance of the word seems to be in 1517 when the Testamenta Eboracensia has “j par sotularium quæ dicuntur stertuppes” (a pair of shoes that are said [to be] stertuppes).
Re-enactors have taken them to be working men’s shoes/boots based on John Withal’s 1574 Dictionary, which says, “In a manner all husbandmen doe Weare Startuppes.” However, in 1572 the Documents for Queen Elizabeth I’s Revels list several pairs of “white startops of cloth of sylver.” Also, in 1608, is “Her neat, fit, startups of green velvet bee, Flourisht with silver.” Neither cloth of silver or green velvet are likely to be worn by husbandmen. But Drayton in 1606 wrote of “a shepheard any thing that could, But greazd his startups black as Autums sloe.”
In 1574 John Baret’s An aluearie, or, Triple dictionarie in Englishe, Latin, and French .. has: “A high shooe of rawe leather called a stertvp”
Randle Holme’s Acadenmy of Armory mentions startops more than once, there is:
“and Startops from the top of the Feet to the middle of the Legg, turned down into Fouldings,”(page221)
“with Startops on his Leggs” (page 243)
OF the Ornaments for … the Feet, as Hose, Startops, Garters, Shoos and Broges (Book 3, C1)
And “Star-tops or hose foulded downe belowe the knees.”
By the eighteenth century and into the nineteenth century startups only appear in dialect dictionaries, and usually indicate leggings
Startops, ..stirtups, a Kind of Button'd Buskins—Not High Shoes as Littleton represents them This is from Horæ Subsecivæ (MS Bodl. Eng. lang. d.66) 411, a manuscript glossary of words compiled by Robert Wight of Wotton-under-Edge in c .1777.
Start-ups, short gaiters: long ones being styled leggings. This is from Anne Baker’s Glossary of Northamptonshire words and phrases published in 1854.
So – make your own decision about what starups were in the seventeenth century.