It is not surprising that, despite occasional earlier calls by individuals to establish some sort of national collection, serious moves to create a national library for Wales should have coincided with the growing reassertion in the nineteenth century of the claim of Wales to be treated as a distinct nation and not a mere adjunct to England. An important meeting at the National Eisteddfod in 1873 expressed a strong aspiration to establish a national library. Interim accommodation for a ‘Welsh library’ was offered by the University College of Wales in Aberystwyth, itself newly founded in the previous year.

The argument was not easily won. The most persistent advocate was Sir John Herbert Lewis, MP for the Flint Boroughs, who from 1892 worked tirelessly to secure for Wales a fair share of the Treasury grant for national museums and libraries. The campaign eventually succeeded in 1905 with the announcement that the British government intended to establish a National Museum of Wales in Cardiff and a National Library of Wales in Aberystwyth.

The decision to locate the Library in Aberystwyth owed much to the town's central location within Wales, the existing Welsh collection in the university college, a successful appeal fund and a magnificent site donated by Lord Rendel, as well as to errors of judgement in Cardiff's presentation of its counterclaim. But the deciding factor was undoubtedly the magnificent collection of manuscripts and books built up by Sir John Williams, a retired physician and former medical adviser to the royal family.