The 1984 British Grand Prix was won by what driver who is the only one to have been a champion for both Ferrari and McLaren? 
1984 British Grand Prix: The 1984 British Grand Prix (formally the XXXVII John Player British Grand Prix) was a Formula One motor race held on 22 July 1984 at Brands Hatch, Kent, England. 1984 British Grand Prix:  The 71-lap race was won by Niki Lauda in a McLaren-TAG, with local driver Derek Warwick second in a Renault and Ayrton Senna third in a Toleman-Hart. Niki Lauda:  He is currently the only driver to have been champion for both Ferrari and McLaren, the sport's two most successful constructors.
Niki Lauda