Definition of "one-day"

On the morning after the one-day strike, October 4, one of the Type 4s on crew-training, No. D169, was appropriated to head the 3 a.m. mail to Hull, as no steam locomotive had been lit up and the usual Hull Type 3 was not available; [...].

1962 December, “Motive Power Miscellany: North Eastern Region”, in Modern Railways, pages 422, 425