Переведите в passive voice: The British have traditionally based their food on beef , lamb,pork,chicken and fish.
The British food traditionally has been based on beef , lamb,pork,chicken and fish. - Британская еда традиционно основана на говядине, баранине, свинине, курице и рыбе.
Their food has traditionally been based on beef,lamb,pork,chicken and fish by the British.