Home Secretary David Blunkett has refused to grant diplomatic immunity to armed American special agents and snipers travelling to Britain as part of President Bush's entourage this week.
In the case of the accidental shooting of a protester, the Americans in Bush's protection squad will face justice in a British court as would any other visitor, the Home Office has confirmed.
The issue of immunity is one of a series of extraordinary US demands turned down by Ministers and Downing Street during preparations for the Bush visit.
These included the closure of the Tube network, the use of US air force planes and helicopters and the shipping in of battlefield weaponry to use against rioters.
In return, the British authorities agreed numerous concessions, including the creation of a 'sterile zone' around the President with a series of road closures in central London and a security cordon keeping the public away from his cavalcade.
The White House initially demanded the closure of all Tube lines under parts of London to be visited during the trip. But British officials dismissed the idea that a suicide bomber could kill the President by blowing up a Tube train. Ministers are also believed to have dismissed suggestions that a 'sterile zone' around the President should be policed entirely by American special agents and military.
Demands for the US air force to patrol above London with fighter aircraft and Black Hawk helicopters have also been turned down.
The President's protection force will be armed - as Tony Blair's is when he travels abroad - and around 250 secret service agents will fly in with Bush, but operational control will remain with the Metropolitan Police.
The Americans had also wanted to travel with a piece of military hardware called a 'mini-gun', which usually forms part of the mobile armoury in the presidential cavalcade. It is fired from a tank and can kill dozens of people. One manufacturer's description reads: 'Due to the small calibre of the round, the mini-gun can be used practically anywhere. This is especially helpful during peacekeeping deployments.'
Ministers have made clear to Washington that the firepower of the mini-gun will not be available during the state visit to Britain. In return, the Government has agreed to close off much of Whitehall during the visit - the usual practice in Britain is to use police outriders to close roads as the cavalcade passes to cause minimal disruption to traffic.
A Home Office spokeswoman said: 'Negotiations between here and the US have been perfectly amicable. If there have been requests, they have not posed any problems.'
An internal memo sent to Cabinet Office staff and leaked to the press this weekend urged staff to work from home if at possible during the presidential visit. Serious disruption would be caused by 'the President Bush vehicle entourage requesting cleared secured vehicle routes around London and the security cordons creating a sterile zone around him'.
Meanwhile, negotiations are continuing between police and demonstrators about the route of the march. Representatives of the Stop the War Coalition will meet police at Scotland Yard tomorrow to discuss whether protesters will be able to march through Parliament Square and Whitehall. Spokesman Andrew Burgin said he hoped for 'a good old-fashioned British compromise'.
Sorry Britain. Australia has already had first go at brown-nosing Dubya. (And did it in spades.) We have first dibs on being the 51st state. However (if you don't mind a bit of gratuitous advice from an inmate of one of your former penal colonies) it seems that you limeys are not going about it in the right way to sew up the 52nd star on the flag. For one, you chaps need to ship that uncooperative commie bastard Blunkett off to Guantanamo Bay tout sweet.
"a 'sterile zone' around the President "?!? Oh, oh, oh! If I were one for cheap shots now would be the moment for me to pull out one of those lovely sounding 'mini-guns'.