Boris Johnson on Monday said ministers will “not hesitate” to impose a quarantine system for travellers from other countries to the UK if needed.It comes as the rise of coronavirus cases in other countries could see more added to the 'Red List' of places travellers need to self-isolate on return.The Prime Minister said: “I don’t want to advise people about their individual holidays, individual decisions, they should look at the travel advice from the Foreign Office clearly.“But what I will say,