Metropolitan Police Commissioner Sir Ian Blair has concluded the explosions were a "co-ordinated" attack on the Underground and buses.
Terrorism expert Professor Eric Moonman told Sky News: "Because of what is going on Scotland some of the twisted minds of the terrorists will all want to claim credit for this action. There will be a lot of people who will want to say we did it."
Prof Moonman added terrorists are "attracted" to areas which are crowded with people.
"It's where the normal public go day-to-day that is always an attraction for the terrorist mind," he said.
"It's a twisted mind and that's why we're finding that the heart of London is almost closed down.
"The bus is a public vehicle and this is what was found in Madrid and what the Israelis have to live with because they know it produces the most terrible and terrifying of pictures and it makes a story.
"We haven't been up to the mark on this... nevertheless, this isn't the moment to apportion blame. But there is a massive job to be done, confidence has to be restored and then we have to start to think about where they are coming from.
"The fact is, you can do any crime if you really want to."
Professor Paul Wilkinson, director of the Research Institute for the Study of Terrorism and Political Violence, said: "It is quite clear that a major terrorist attack has been carried out on London.