The team base is a reference to the town and country where the team’s headquarters and Each team has a home base where the factory is typically based. From there teams of talented people, design, model... are located.
Home to the designers, fabricators and all of the support personnel. Often referred to as the factory.
Today many of the teams are based in the UK which is a legacy of the sport’s inception where it was beneficial for teams to be located close to engineering and testing facilities.