Butler was working as an architect when the Second World War broke out. He became a conscientious objector, and spent the war years working as a blacksmith and repairing farm equipment. At the end of the war he resolved to become a sculptor. His first works were strongly influenced by Henry Moore, especially the older sculptor's Three Standing Figures, 1948 (Battersea Park, London). Butler's early sculptures, culminating in the The Unknown Political Prisoner, 1952, are predominantly linear in conception. They were often forged in iron, a skill he learned as a blacksmith.

Penrose noted in the introduction to an important exhibition of works by Butler at the Curt Valentin Gallery in New York in 1953:

Reg Butler's forms are basically human and like
the human frame they are hollow. His earlier figures
existed as linear shapes in wrought-iron, united by
interpenetration of the essential elements of their
structure. More recently his mastery of other
mediums leads him to present us with surfaces which
hide the inner void but still leave us conscious of
vital forms within. There is continuous play
between the receptive aspect's cavernous interiors,
limbs, like radar antennae, stretching towards
invisible and inaudible waves and the aggresive
fullness of form, ready to penetrate like a
battering ram.

These figures are not solidly based on earth but
practice levitation. They are airborne and the
upward gaze of the taunt, phallic heads lift them
even further from the ground, raising them in the
imagination to the dimensions of inter-stellar
space. (exh. cat., New York, Curt Valentin Gallery,
Reg Butler, 1953)