A later historian of Welsh architecture, Peter Smith, described Fox and Raglan’s work as equal in importance, in its own field, to Charles Darwin's On the Origin of Species.

[a] He would identify houses of interest and obtain the necessary permissions from owners, before calling in Fox to undertake a detailed survey.

Wartime defensive precautions in 1941 led to a decision by the Ministry of Works to demolish an important farmhouse, Upper Wern-hir, near Llanbadoc.

[8] Working mainly at weekends, and funded by the National Museum, Fox and Raglan produced "the first truly comprehensive regional study of vernacular architecture in Britain".

[10][11] The architectural historian, John Newman, author of the Pevsner for Monmouthshire, considered their joint work as "ground-breaking, the single most important publication on any aspect of the county's buildings",[12] and Smith described Monmouthshire Houses as "one of the most remarkable studies of vernacular architecture yet made in the British Isles",[13] "a landmark, in its own field, as significant as Darwin's Origin of Species".