America can have a Black head of state, but Britain can't. African-Caribbean and Asian Britons are barred by the system of hereditary monarchy. As Barack Obama celebrates his 100 days as the first Black US President, a majority of Britons remain content to support an implicitly racist monarchical system that denies people the same colour as him the opportunity to hold the office of head of state in the UK.
Obama has broken the race barrier and assumed the role of US head of state, but the race barrier remains firmly intact in the UK. For the foreseeable future, non-white people are ineligible to head our nation.
Under Britain's constitutional system, the head of state is the monarch - at present Queen Elizabeth II, head of the House of Windsor. The position of monarch and head of state is inherited through the Windsor family line. The Windsors are white and only their descendants are eligible to be monarch and British head of state. The result is a de facto race bar.
When the Queen dies, her role as head of state will pass to her first-born son, Charles. When he is dead, the title will pass to his first-born son, William, and so on. From white person to white person to white person. Under this system, Black people are excluded. The all-white Windsor family has the exclusive franchise on the office of head of state.
It is true that if a future monarch married a non-white person, their first born child could ascend to the throne and become head of state. But this is a matter of "if" and "could". Not will. There is no guarantee at all. In any case, why should Black Britons have to wait in line for generations? It is a vile insult to make them stand at the back of the queue.
A head of state is supposed to represent the nation and its people, and to symbolise its values and culture. In a diverse multi-ethnic society such as Britain, surely it is wrong to automatically, a priori deny this honoured, revered role to non-white citizens?
Whichever way the defenders of monarchy try to spin it, there is no escaping the fact that the head of state position is open to only the white Windsors. Non-white people are shut out for decades to come, and possibly much longer. They cannot hold the title of British head of state (nor can many other Britons, including other white ones, but that is another issue).
This makes the current method of appointing the head of state racist by default. Although it was not devised with racist intent, it is racist in effect. Drawing on the analysis and conclusions of the milestone MacPherson Report about the the racist murder of Black teenager Stephen Lawrence, the current method of appointing our head of state is institutionally racist. The system favours one race over others. Non-white people are excluded, for decades to come and possibly much longer. This makes it a de facto racist system.
Equally appalling, this exclusion of non-white Britons excites no public outrage, not even from liberals, the left and anti-racist and Black pressure groups. They just accept it as "the British way" of doing things. Only the Green Party is calling for a democratically elected head of state. For the big three political parties - Labour, Conservative and Liberal Democrat - an inherited whites-only head of state is no cause for concern and does not need reform.
The monarchical system may still command majority support. But this manner of determining Britain's head of state is surely an offensive, bigoted anachronism. It is premised on the assumption that the most ignorant, stupid, immoral white Windsor is more entitled to be head of state than the best-informed, wisest and most moral Black Briton. This is a truly repulsive racist assumption.
It is time the British head of state was chosen by the people, based on the quality of their character and not on their white royal parentage and aristocratic blood-line.
• Peter Tatchell is a leading member of the Green Party. For more information about his human rights campaigns and to make a donation: www.petertatchell.net