There is a barrier to a British Obama breaking through - or a British Sarah Palin, or a British Jimmy Carter.
It hasn't got anything to do with race - its called the Parliamentary system.
No post-war British Prime Minister has taken up the office less than a decade after entering Parliament - it took John Major eleven years to be chosen to replace Margaret Thatcher.
That means a Sadiq Khan, or Kitty Ussher, or Ed Vaizey is going to have to wait to lead their party. David Cameron is unusual (as Iain Duncan Smith would have been) in that he will lead his party at a general election just eight or nine years after entering Parliament. But Obama was elected to the Senate in 2006. Nobody knew who Carter was a year before the governor of Georgia became President.
We need to open up the culture of party politics – as David Lammy and other leading MPs have recognised. That is about tapping in to the new forces for progressive change in the future – about learning from what Obama has achieved in bringing a new generation into poltics; about new forms of campaigning and mobilising. Its about changing our politics. One good starting point would be for Labour to hold an open primary for its candidate to take on Boris Johnson in London in 2012.
Here are the post-war Prime Ministers - and how long it was between their being elected to Parliament before becoming PM.
1945: Clement Attlee (1922; 23 years),
1951: Winston Churchill (1900; 51 years this time; 40 years the first time around in 1940).
1955: Anthony Eden (1923; 32 years)
1956: Harold Macmillan (1924; 32 years after elected, though with a gap between 1929 and 1931)
1963: Sir Alec Douglas-Home ( House of Commons 1931: PM 32 years later; though gap 1945-50)
1964: Harold Wilson (1945; 19 years)
1970: Edward Heath (1950; 20 years)
1974: Harold Wilson (29 years, this time around)
1976: Jim Callaghan (1945; 31 years)
1979: Margaret Thatcher (1959; 20 years)
1990: John Major (1979; 11 years)
1997: Tony Blair (1983; 14 years)
2007: Gordon Brown (1983; 24 years)
UPDATE: Have now had a chance to fill in a gap from earlier, having simply noted Douglas-Home's peerage.
That allows a calculation that the average is 26 years from entering Parliament to becoming Prime Minister. (It falls to just under 25 years if Wilson's second Premiership is omitted, and if Churchill is calculated on his experience in 1940, not 1951). But this has fallen to an average of 17 years and 3 months in post-1979 premiers. It is noticeable that we have only had four Prime Ministers in almost 30 years - though Obama will also be only the fifth US President since 1980, following Reagan, Bush Sr, Clinton and Bush Jr.
Though Alec Douglas Home is probably the least known post-war Prime Minister, there is an exceptionally good biography of him by DR Thorpe, and his extraordinary career captures much about the Conservative Party in the mid-20th century. Douglas-Home entered the Commons in 1931 (having failed to win a seat in 1929) and served in every Tory administration between Baldwin's government in 1935 through to the Heath government until Feb 1974, when he was a Foreign Secretary. He was in the Commons 1931-45, out from 1945-50; re-elected as an MP in 1950 but disqualified as an MP on the inheritance of a peerage in 1951, renouncing the title on becoming PM in 1963, re-entering the Commons 1963-74; then back to the Lords).
The consummate political insider! The consequences of his emergence as leader in 1963 was also thought to have ended both the aristocratic dominance of Tory politics: many thought he would be the last Old Etonian PM, especially after the manner in which Douglas Hurd lost the 1990 leadership contest. But Mr Cameron has proved that it is possible for an Old Etonian to be party leader again.