There were two Joan Eardleys, according to a new biography of the Scottish painter by Christopher Andreae. There was ‘the tender and gentle Joan’, as revealed by her bosom friend Audrey Walker, and ‘the tough, cussing, swearing, bulldozing, indomitable creator of what may be masterpieces’. Both are reflected in the Portland Gallery’s new exhibition of drawings and paintings from the last 20 years of her short life (until 17 May).