Jim
Both of those tunes were only mid level or minor chart hits in the USA but I don't think they were well known or maybe even released widely in the UK at the time they came out.
The British players and singers often covered these obscure songs, there sometimes being a way whereby they discovered them and were able to access new material (A&R men and DJs and record company people who had advance copies, a few local record shops that imported US stuff- like NEMS in Liverpool, and some shops in London etc)
From comments I've heard from some US artists who benefited greatly from British covers which became huge hits, they may not have liked the cover versions or that others were taking their songs into the charts, nor did they often know or care who the hell these Brit kids were, BUT they were grateful and happy when the royalty cheques hit their mail boxes!
I saw the great Latin jazz timbale player Tito Puente and his band play some years ago, and introducing his tune 'Oyo Como Va' he said that he didn't like the rock cover version when he heard it and hadn't heard of this Santana bloke- but after the cheque arrived, he said he LOVED Santana..!