 The regiment apparently did not mechanise before the outbreak of the Second World War; after mobilisation, it was converted to the artillery role.It transferred into the Royal Artillery in February 1940 as "155th (Lanarkshire Yeomanry) Field Regiment, RA"; in April 1940, "156th (Lanarkshire Yeomanry) Field Regiment, RA" was formed as a second-line duplicate.Both served as field artillery regiments.