Christine Pullein-Thompson

The Pullein-Thompson sisters – Josephine Pullein-Thompson (3 April 1924 – 19 June 2014), Diana Pullein-Thompson (1 October 1925 – 21 October 2015), and Christine Pullein-Thompson (1 October 1925 – 2 December 2005) – were British writers, known mainly for their pony books, mostly fictional, aimed at children and mostly popular with girls. https://en.wikipedia.org/wiki/Pullein-Thompson_sisters