Yep:
Parliament had reassembled on January 27[, 1377,] with [Crown] Prince Richard [of Bordeaux] and John of Gaunt [Duke of Lancaster] presiding.... [D]isturbing rumors that John of Gaunt was a changeling were causing "great noise and great clamor."... They appear to have been spread by the banished [Bishop] William of Wykeham... in a bid to topple the duke.... It was asserted that... Queen Philippa actually gave birth to a daughter but overlaid and suffocated her. Fearful of confessing this to King Edwards, she substituted... a living boy, the son of a Ghent laborer, butcher, or porter... smuggled into St. Bavoon's Abbey... named him John and brought him up as her own. Philippa was said to have admitted this in confession to [Bishop] William of Wykeham on her deathbed in 1369k insisting that should there ever arise any prospect of John succeeding to th throne the bishop must break the seal of the confessional and publicly reeal the truth...
Alison Weir (2009), Mistress of the Monarchy: The Life of Katherine Swynford, Duchess of Lancaster (New York: Ballantine: 9780345453255), p. 161.
