 C. H. Josten has speculated that Backhouse associated with the prominent Rosicrucian Robert Fludd (who had become a member of the college in 1605), though there is no hard evidence to support such an association.Further, Mordechai Feingold has speculated Backhouse formed a bond with Robert Payne over their common Berkshire heritage, college, and scientific interests.No evidence has survived of their association during this period, but circumstantial evidence corroborates the statement and they were certainly good friends in later life; Payne staying in Backhouse's Swallowfield estate after his 1648 ejection from Oxford during the parliamentary visitation, and continuing to pay visits long after.