There is a subscription site called Rootsireland.ie They have records taken from the registers.The Civil Death Record of William Brown on 25 March 1872 shows the details as given by Gaffy. It is rarely that they show cause of death, the informant on record it sometimes gives the relationship to deceased as with the record of Honor Brown in 1883 noted that Bridget Brown was her daughter in law.
A lot of people from the Islands are buried in the OLD Kilmeena Cemetery,i am not sure if any people were buried on the Islands but I would say not, you could contact the Westport Clew Bay Heritage centre and ask.The Islands come under the Kilmeena Parish,i presume that once William Brown died his wife Honor moved to the house in Knockfin,the home of her daughter in Laws people.The people from Knockfin would most likely be buried in Oughval sp Aughvale cemetery.
You can purchase the book via Amazon,there is details of what it contains.The smaller Islands would not have been big enough to support a living for people but the larger ones certainly had many people back from 1840c. Clare Island is one of the larger Island and is very popular with tourists, they have boats going over daily, as with the Collanmore Island Lodge.
Irish research is difficult the biggest hurdle is identifying the Townland your family came from, the fact you have found Collanbeg is a huge breakthrough.
