Complex sentence: The height of Kar's success was her Whitechapel Gallery solo exhibition in 1960, her closest assistant John Couzins' family recently contributed to a tribute exhibition of Ida's work at the NPGm his archive having been compiled after his unfortunate death by Richard Taylor of Folkestone.
Split into simpler sentences: The height of Kar's success was her Whitechapel Gallery solo exhibition in 1960. The family of her closest assistant, John Couzins, contributed to a tribute exhibition of Ida Kar's work at the NPGm-his archive having been compiled after his death by Richard Taylor of Folkestone.