Many of them, though, are also owned by foreigners.
For some "British" brands, it's well-known they have foreign owners: Surely everyone is aware that Harrods was bought by Qatar Holdings in 2010? And before that it was owned by the Fayed brothers of Egypt?
But others are more discreet about their proprietors. They know that the Brits occasionally fight for their companies to stay in British hands, like when MPs went to bat against Kraft's takeover of Cadbury in 2011.