Today is the first time Parliament dissolves automatically, thanks to the Fixed Term Parliaments Act, so there is absolutely no need for the Prime Minister to drive a mile down the road to ask the Queen to close off another five-year session of law making.
In a sign of how modern Britain is becoming, the monarch no longer has the prerogative to close Parliament - which makes today’s trip one of the most pointless in politics.
Previously it was up to the sitting Prime Minister as to when he or she decided to dissolve Parliament, but they had to seek the monarch’s permission.
But from hearing her purr one more time to ruining Ed Miliband’s big business pitch, there plenty of reasons why Cameron and his deputy Nick Clegg will visit Buckingham Palace today.
The Lib Dem leader gets to tag along because as Her Majesty’s president of the Privy Council, he needs to be there when she signs the documents.
He gets to bid farewell to the Queen
It could be the last time he gets a private meeting with the Queen. He has met her weekly throughout his premiership but that privilege will be gone if he fails to remain as Prime Minister in May.
One last purr
Cameron loves all the trappings of his job’s traditions and he loves to hear the Queen “purr”.
The Prime Minister was forced to apologise after embarrassingly revealing that Her Majesty “purred down the line” when he told her the Scotland had voted against independence last September.
Stealing Miliband’s thunder
He has chosen to visit the Palace at around the same time as Ed Miliband’s big moment to woo business over to Labour by announcing the party’s business leaders alongside Ed Balls and Chuka Umunna.
He will steal the Labour leader’s thunder as the news channels deploy helicopters to follow Cameron’s last journey to Buckingham Palace and back.
Big boy Cameron: another PR stunt
Cameron used to work as in PR so he knows how and when to milk a good PR stunt. It is yet another event that makes him look that much more prime ministerial and statesman-like compared to Ed Miliband.
Just like his trip to Washington in January, the photo-ops of looking important alongside head of states are worth it.
The British public love a bit of royal theatre and Cameron will hope crowds will gather to make him look popular.
He can use it as yet another election launchpad
We've had many 'starting guns' for the election and this trip to the Palace allows the Prime Minister to launch yet another.
He'll return to the steps of Downing Street where he'll tell voters they offer a 'stark choice' between the Conservative party and Labour and will finally be able to shed himself of Clegg and the Lib Dems.