Howells of Martletwy

Hi all,
I have been trying to trace any information on my 5 x Gt Grandfather a Wm Howells not sure where he was born, what I do know that he was born around 1770-1780's he did have son called George b 1811 who was born in Martletwy Pembrokeshire. Just wondering has anyone who are searching the Howells surname has ever come across this person.

Many thanks

Rowland Howells