Surely for the terrorist on a budget it would be cheaper to charter a small boat on the Thames to attack Parliament. Or even better value, just hire a cab "over-power" the driver and drive up to the House of Commons! At least that way any attack won't be foiled due to bad weather.
Maybe if the Daily Mirror ran the capital they would check everyone's bags in the City, just to be on the safe side.
Don't journalists have anything better to do these days??