Hannah Frank did these (unsigned) pastel drawings in the 1950s at the Glasgow School of Art as part of life drawing classes.  They lay unnoticed in an old suitcase for 50 years until just before the centenary exhibition at Glasgow University, where they were found by her niece and exhibited with her black and white drawings. Some are available for sale, framed, at £900. contact by email hannahfrankart at gmail.com for availability.