Here is a similar case, but with lots of asterisks. :)
James Boyd, later Hay (1726-1778), called Lord Boyd as heir apparent of his father, the 4th Earl of Kilmarnock, never succeeded his father, but only because his father was attainted and executed in 1746. However, he did succeed his maternal great-aunt in 1758 as 15th Earl of Erroll. However, he had never been heir apparent, only heir presumptive, to his great-aunt.