According to the Archives of Montres Omega, the present anti-magnetic single button chronograph wristwatch was sold to Italy in 1928.
Early oversized single button chronograph wristwatches in such beautiful, original condition such as the present watch are exceedingly rare. Another particularity is the chronograph button, placed between the lower lugs to the 6 o'clock position instead of the more common placement in the band or in the crown.
A similar watch is illustrated and described in Omega - A Journey Through Time by Marco Richon, p. 527, pl. 8178.