As Ireland recovered from the Famine in the late 19th century, Carroll was able to gain considerable experience designing country houses, ornate churches and public buildings.

He presented designs at the Royal Dublin Society's Exhibition of Fine Arts in 1861 and was later chosen as the lead architect for British Prime Minister Lord Palmerston's estate home at Mullaghmore, County Sligo.

[4] As a result of changing social conditions in rural Ireland, most of the projects undertaken by Carroll & Batchelor were large public works concentrated in County Dublin.

[5] His obituary in the Irish Builder described him as: a kindly, upright, courteous gentleman', whose 'clients were in a real sense his friends, no trouble was too great for him to take; indeed, his attention to detail was extraordinary, and therein lay the secret of much of his success.The nature of Carroll's work was very heavily influenced by the social conditions of his day.

Work on such projects all but dried up by 1890 and Carroll spent the last decade of his career overseeing the design or remodelling of public buildings, especially hospitals.