Optically stimulated luminescence (OSL) has been used to date silts, interpreted as either primary or colluviated loess, deposited in karstic depressions at three sites on the Carboniferous limestone of NW England. Two of the ages presented here constrain the onset of the last (Late Devensian) ice in this region to later than ca. 27 ± 2 ka, and the other two date initial deglaciation prior to ca. 19 ± 2 ka in the Morecambe Bay area and ca. 17 ± 2 ka in the karst of the Yorkshire Dales. While these ages are broadly consistent with existing estimates from lacustrine and speleothem evidence, they offer the tightest constraints yet published on the presence of the last ice sheet from northern England. Copyright © 2009 John Wiley & Sons, Ltd.