If it had been Inglethorp who was carrying on an intrigue with Mrs. Raikes, his silence was perfectly comprehensible. 
Inglethorp definitely did have an affair with Mrs. Raikes.
mnli hypothesis: Inglethorp definitely did have an affair with Mrs. Raikes. premise: If it had been Inglethorp who was carrying on an intrigue with Mrs. Raikes, his silence was perfectly comprehensible. 