Complex sentence: By the early 1930s she opted to teach part time so as to develop her own painting, for 14 years attending summer landscape painting courses run by Reginald St Clair Marston.
Split into simpler sentences: By the early 1930s she had opted to teach part time so as to develop her own painting. For some 14 years Wickham attended summer landscape painting courses run by Reginald St Clair Marston.