Mann made a number of genuinely innovative breakthroughs and certainly had the potential to become one of the most important figurative painters of his time. Yet struggling with mental health problems Mann had an unerring instinct for turning each moment of promise into bitter disappointment. In 1959, Renske van Slooten fell in love with Mann who was more than twice her age. Renske was convinced she discovered a genius and she promised to dedicate her life to him as muse, model, and money earner. Their struggles quickly threatened to overwhelm them.

The Girl in a Green Jumper is not only an enthralling story set against the backdrop of 1960s London, but it also charts in detail the struggles an artist goes through, both creatively and financially. Renske also gives fascinating insights into the way that Cyril's painting technique evolved over time.