Peter Ritchie Calder was born on 1 July 1906 in Forfar, Scotland, the youngest of four children of David Lindsay Calder, a linen worker, and Georgina Ritchie, the daughter of a master mason.
Peter Ritchie Calder was born on 1 July 1906 in Forfar, Scotland, as one of four children to David Lindsay Calder, a laborer in the textile sector, and Georgina Ritchie, the offspring of a skilled artisan.