I think that the traditional guards at London palaces should be replaced with armed soldiers. According to my college Spanish teacher, the Palacio Real (Spanish equivalent of Buckingham, it's where King Juan Carlos lives) as well as other places like the main court, are guarded by army troops with submachine guns, and they DO mean business, and will not hesitate to point their guns at anyone. Spain has had decades of experience with homegrown terror, so they wisely junked tradition and went for the jugular. I'm surprised that Britain, with all the grief that the IRA gave them, hadn't replaced the traditional guards with real soldiers ages ago.
Since 9-11 the US Capitol and the White House have been guarded by Marines, and they do not let tourists anywhere near them, they don't even do tours anymore, the tourists have to look at the buildings from raised bulletproof platforms a half mile away, and all purses are confiscated and all pockets emptied lest any terrorist think of drawing diagrams. Downtown Washington has so many barricades and blast walls it's more like Baghdad. Some people here may remember when President Clinton closed Pennsylvania Avenue in front of the WH a dozen years ago, and bicyclists and rollerbladers glided by past the WH fence. Well, NOBODY except the Marines are allowed there anymore.
Rumor is they've made it so that the Capitol-WH area could function as a Green Zone during mass chaos in the US, the politicians would bed down in the basement of the Capitol and food would be helicoptered in. Self-contained power and water supplies and everything. The UK needs to get serious about guarding the royals and can those guards in favor of REAL guards, soldiers in uniform with guns who mean business. The tourists tend to forget that those guys have a real job to do. With real Marines, I assume that mistake would not occur.