Counter-Terrorism and Security Bill

I wonder if the Minister could consider a concrete and perhaps not too remote example. Let us suppose the authorities in the United States were to send an e-mail to the authorities in this country, saying that X should be stopped; he is passing in transit through the UK and going to Ukraine— for instance—for terrorism purposes. Would that be reasonable grounds for stopping him and removing his passport? I would like the Minister to consider that. There would be no evidence or intelligence in the hands of the British authorities. A reason given to the passenger could, I suppose, be that their country says that their passport must be taken away; but would that be reasonable grounds? Could that possibly be the basis of the decision by the policeman or immigration officer?