SILVERSTONE, England, July 15 (Reuters) - McLaren Chief Executive Zak Brown is isolating after testing positive for COVID-19 but the team"s preparations for their home British Grand Prix at Silverstone this weekend remain unaffected, the team said on Thursday. McLaren said two other team members had also tested positive in unconnected cases. It added that the drivers, Australian Daniel Ricciardo and Britain"s Lando Norris, were not in close contact with those affected. The team are third in the Formula One championship, with principal Andreas Seidl overseeing day to day operations and reporting to Brown.