Rhodri ap Gruffudd or Prince Rhodri was the third son of Gruffudd ap Llywelyn. He was the younger brother of both Llywelyn ap Gruffudd (Llywelyn III of Gwynedd, Prince of Wales) and of Owain ap Gruffudd. He was the older brother of Dafydd ap Gruffudd (Dafydd III of Gwynedd.
Rhodri was born in the early 1230's the son of Gruffudd ap Llywelyn the illegimate but eldest son of Llywelyn ap Iowerth (also known as Llywelyn II Fawr). Little is known about his early life except that on his grandfather's death in 1240 his uncle Dafydd ap Llywelyn (his father's younger, but legitimate, half brother) inherited the throne and immediately imprisoned his father - thus disinheriting him. Gruffudd was subsequently captured by the English during the war of 1241 and taken to London as a hostage where he died in 1244 after trying to escape from the Tower of London.
Everything changed in 1246 when his uncle Dafydd, the Prince of Wales, died without issue and the throne was inherited under Welsh Law by the four sons of the now dead Gruffudd. A massive struggle ensued between them all but by the 1250's his charismatic older brother Llywelyn had consolidated his position and successfully excluded the other siblings from power. Rhodri alone appears to have avoided getting involved in the fighting and by 1272 had agreed to sell his inheritance rights to Llywelyn. He immediately left Wales to live in exile in England probably because he was keen to avoid the same incarceration suffered by both his father and by his older brother Owain.
Rhodri appears to have moved initially to Cheshire before buying a farmstead in Surrey where he lived until his death in c.1300. As the only surviving brother of Llywelyn III after 1283 he would have been regarded by many as the true, but unproclaimed, King of Gwynedd and Prince of Wales. This factor, and Edward I's desire to completely exsponge the Welsh state, would have made the latter part of his life extremely precarious.
He is known to have had at least one son, Thomas ap Rhodri, who was the father to Owain Lawgoch.
Academic research by Professor Tony Carr has indicated that the manor of Tatsfield in Surrey was in the possession of Rhodri ap Gruffudd and his descendants during the 14th century. Rhodri’s son, Thomas ap Rhodri, and his grandson, Owain ap Thomas (Owain Lawgoch), may have been born in Tatsfield. Owain Lawgoch eventually became one of France’s leading mercenary captains fighting against the English during the 1360’s and 1370’s and was eventually assassinated in 1378 under the orders of the English Crown because of the threat he presented to the political stability of Wales after he declared himself to be the Prince of Wales.
Documentary sources suggested Tatsfield manor house was demolished in 1801 however the investigations revealed that Thomas had borrowed money to build a new house during the 1320’s and that his house and associated complex had been systematically dismantled at the end of the 14th century, most probably under the orders of the English Crown and in a very similar fashion to the way such llys or palace complexes were removed by Edward I in Wales.
Source: "The end of The House of Gwynedd: Excavation of a Medieval Welsh Manor Complex in Tatsfield, Surrey" by Spencer Smith