This is not the William who was son of the parents he's connected to. Notice Elizabeth Bowerman was born in 1679 and therefore wasn't even born when this William was born. His Wikipedia page gives the dates of his parents but no maiden name for his mother. The confusion has come into play due to his parents were named William and Elizabeth but with totally different birth and death dates. The error has been entered into many personal trees, thus perpetuating the error.
https://en.wikipedia.org/wiki/William_Blakeney,_1st_Baron_Blakeney