The Robledo brother were only "half foreign" (which you could pretty well say of any Geordie..:-) ), their mother was English and they grew up (from age 4) in England and spoke English.
There were a few Foreign players in the early seventies like Colin Viljoen (South African).
When the EPL debuted in 1991 there were just 11 foreign players playing on the opening day, now there are 260 registered.
Chelsea are often cited as as the worst of the teams of "Foreign Mercenaries" yet ironically they contribute more players to the England squad than any other Club (J Cole, A Cole, Terry (captain), Lampard, Wright-Phillips, and Bridge).