Thank you for taking the time to read my question

My father was born in kenya and registered as a british citizen (with the right of abode) in 1973. Please keep in mind, kenya got her independence around 1964. His parents at that time were both british subjects.
My dad then gave up his citizenship in 1979 inorder to keep his kenyan citizenship.
My question is, can my dad apply to get his citizenship back? if so, what is the process and what are the requirements.
Any help or advise would be highly appreciated.
Thank you
Regards
shy.