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The title Baron Butler was created in the Peerage of England in 1666.
Baron Butler of Moore Park, Co. Hertford, was created in the Peerage of England in 1666, for Thomas Butler, 6th Earl of Ossory (the eldest son of the 1st Duke of Ormonde). Four years previously, he had been called up to the Irish House of Lords by a writ of acceleration as the Earl of Ossory. As the Baron predeceased his father, his son James inherited the barony in 1680 and then the dukedom in 1688. However, in 1715 his English titles were attainted because of his part in the Jacobite rising. The title was able to pass through the female line and in 1871, the attainder was reversed for the great-great-great-great-grand-nephew of the second duke, the 7th Earl Cowper. Lord Cowper died without heirs, however, and the title has been abeyant since 1905.
The co-heirs to the barony are the descendants of the sisters of the third baron: