A former spy chief has said she is "alarmed" by the number of people using mobile phones and listening to music when they should be more alert to the danger of a potential terror attack on the streets.
Baroness Neville-Jones, a former security minister, said people had to take personal responsibility and be aware of their surroundings.
The former head of the Joint Intelligence Committee suggested that people would have to get used to disruption to their daily lives as a result of counter-terrorism operations and security scares.
Official guidance is for people to be "alert but not alarmed" at the threat from terrorism, but Lady Neville-Jones suggested citizens were not as vigilant as they could be.
"I think being alert is very important. I am alarmed by the number of people I see wandering along the street entirely engaged in their mobile telephones and with their ears plugged into music and they are not aware of their surroundings. You need to be aware of your surroundings," she told BBC Radio 4's Today programme.
"You do have to take some personal responsibility."
She added: "I do think we can be more alert than we are."
Lady Neville-Jones said action such as that taken in Munich, where two railway stations were closed on New Year's Eve in response to a suspected terror threat, would become more likely.
The stations reopened yesterday after German officials said there was no sign of any imminent terror attack.
"I do think we are going to have to get used to what we have seen yesterday in Germany - that is to say alerts which close places of public functions, and higher levels of security in big public gatherings. That is prudence and proper caution on the part of intelligence and the police authorities."
She said the authorities had to take any intelligence seriously: "If you have got a piece of information, it may be difficult for you to assess it, you may not be comfortable about having a broader picture - part of the problem with intelligence is it can be fragmentary - but it's a very bold government or policeman who chooses not to take precautions in such circumstances.
"I think the population on the whole would prefer them to be cautious and occasionally have closed something that it turned out wasn't necessary, but how do we know, rather than take the risk of exposing people to dangers on which they have information, even if it's not complete and on which they can't necessarily totally rely."
But she played down the prospect of British cities being locked down in the way Brussels had been, highlighting the British authorities' experience of coping with terrorism.
"I would hope that that would not be something that would happen in the UK. I do think that counter-terrorism and both the intelligence side of it and the policing side of it, and well done, are matters which are bred of long experience and of great skill and I think that in this country we do have both of those things and we have very close co-operation between both police and agencies and I think they understand how to use information.
"I don't think those skills are nearly so widespread on the continent. So I think we shouldn't conclude that what happened there is necessarily the technique that would be adopted here."