I would go further and say there has not been a British tier one driver since 1973. Mansell was tier 1.5. Then again, I would say the only tier 1 drivers since 1973 are Senna, Prost, Alonso and Hamilton. I am still not convinced by Schumacher. Narrow talent window. Short sprints between pitstops then only Hakkinen was close. Neutral regulations and tyre management skills being required and he was midfield.
I'm not even sure what all this tier rubbish really means, but if we are talking about 1973 onwards, I think Lauda and Piquet belong in that group.