When Robert's son, David II, King of Scotland, became king, he spent some time in English captivity; following his release, in 1357, he restored MacDougall authority over Lorn, effectively cancelling Robert's grant to the MacRory. The 1354 quitclaim, which seems to have been an attempt to ensure peace in just such an eventuality, took automatic effect, splitting Mull from Lorn, and making it subject to the Lordship of the Isles.
When Robert's son, David II, King of Scotland, ascended to the throne, he spent some time in English captivity; after his release in 1357, he reinstated MacDougall authority over Lorn, effectively nullifying Robert's grant to the MacRory. The 1354 quitclaim, which appears to have been an effort to ensure peace under similar circumstances, automatically took effect, dividing Mull from Lorn and subjecting it to the Lordship of the Isles.