According to one wbebsie
life of Riley - very comfortable existence - based on the 1880's music-hall song performed by Pat Rooney about the good life of a character called O'Reilly; the audience would sing the chorus which ended '..are you the O'Reilly who keeps this hotel? Are you the O'Reilly they speak of so well? Are you the O'Reilly they speak of so highly, Gor Blime me O'Reilly, you're looking well'. The expression 'Blimey O'Riley' probably originated here also.