The mapmaps (and schedule)schedules held by the commissioners passed to the [[Inland Revenue]] and(the thesepredecessors of [[HMRC]]) and are now held in the [[The National Archives]] at [[Kew]]<ref>Foot, p.20</ref> (classes IR29 and IR30). AlthoughMost of the maps do not always survive, theextant parish copycopies isare now usually held inat the county record office. The diocesan copies for most Welsh parishes are held in the [[National Library of Wales]] at [[Aberystwyth]]. Prior to the publication of large scale [[Ordnance Survey]] maps in the late nineteenth19th century, tithe maps were frequently copied (in whole or part) for other purposes -: for example toin accompanyconnection with planned railways, or as part of the title deeds fortransferred on a sale of land. More recently, tithe maps and apportionments have often been used asfor referencesreference by genealogists and other historical researchers. For many parishes they provide the only large scale map showing the landscape prior to the [[industrialIndustrial revolutionRevolution]],<ref>Harley, p.35</ref> and they frequently provide the earliest evidence for the [[field system]] in the parish.
