Similar laws in Belgium and Spain have already been amended. Henry Kissinger has described it as a breach of other countries' sovereignty. The Foreign Minister William Hague has actually pledged to change the law, both before and after the election. He needs to follow through on this pledge so that foreign dignitaries no longer need to fear frivolous lawsuits by those pushing a political agenda.
Currently we have a ridiculous situation whereby the law allows anyone to obtain an arrest warrant, from a local magistrate, against a visiting foreign politician or dignitary for an alleged war crime committed anywhere in the world. While this in itself is not illogical, the system has been and is clearly being abused by those with a political agenda against certain groups. It subverts the capacity of the British government to conduct foreign policy by placing all foreigners at the mercy of political activists.
While it is important to prosecute war crimes wherever they occur, such a decision is significant enough that it should only be made by the Attorney General, and not on the whim of a local magistrate court.