Disguised as Indians, they poured out of the Old South Meeting House and headed down Hutchinson Street for Griffin's Wharf. At a packed meeting to condemn the Tea Act, Samuel Adams declared "they had now done all that they could for the salvation of their country". And this was the excuse the patriots needed as they smashed their way through the East India Company chests, dumping some 90,000lb of tea worth nearly £10,000 into Boston harbour.

Today, the Tea Party patriots come dressed in George Washington outfits and Joker masks, with posters accusing President Obama of socialism, communism, even nazism. This remarkable political insurgency, which mushrooms by the month and has both Democrats and Republicans terrified for their congressional seats, regards itself as the true heir to the republic's ideals. Thomas Jefferson's adage, that "the tree of liberty must be refreshed from time to time with the blood of tyrants", is a favoured banner.

And, to be fair to the Tea Party ideologues, they are being faithful to the principles of 1773: both as tax-dodgers and demagogues. For behind all the lofty talk of no taxation without representation, the Boston tea party hid some grubby material truths.

Few in the early 1770s regarded a split from Britain as either possible or preferable. In fact, the American colonies – and New England in particular – had done well out of the British Empire on the back of shipbuilding, whaling and war. Chief among the new merchant class was John Hancock, whose family firm had been built on provisioning the British army and Royal Navy. The capture of Canada – the campaigns against the French and the Spanish – ensured huge military profits for Boston businesses.

But it was when – in the aftermath of the seven years war – the government asked America to start paying its way, that trouble began. By the 1760s the British Treasury was massively in debt, with the costs of empire falling disproportionately on English taxpayers. Not unreasonably George Grenville, the prime minister, wanted the prosperous colonies to accept more of the financial burden. New taxes on foreign imports were introduced together with a professionalised customs administration.

Unfortunately these levies hit Boston hard as it faced a postwar slump. What was more, the big merchants relied extensively on tax-dodging and smuggling for their riches. Cargo ships laden with molasses from the West Indies, wines from Madeira, coffee from the East Indies, textiles and indigo – all slipped into Boston harbour in the dead of night with no duties paid. Even as the New England colonists urged London to hammer Louis XV and protect them from French encirclement, they refused to face up to their fiscal responsibilities.

Time and again, Britain indulged their wants. The Townshend Duties on foreign imports were reversed, the Stamp Act taxing newspaper and pamphlets was dropped, but it would not give in on the 1773 Tea Act. The legislation was designed to shore up the finances of the East India Company, carve out the Boston harbour crooks, and deliver cheap tea to the colonies. All of which posed an unacceptable threat to the Boston Brahmins. Far from being a spontaneous outpouring of liberty, the "tea party" was brewed up by wealthy merchants worried their secret deals on tea imports were about to be exposed.

And so today, once more, wealthy corporate interests are winding up an angry populace – amid an economic slump – with spurious talk of freedom. Having enjoyed the benefits of their own empire for the last 50 years and pocketed tax cuts during the Iraq war, the 21st-century Tea Party movement is now grumbling about paying for power.

Of course, there are some differences. Today the Tea Party is a suburban, rather than urban, phenomenon; its Fox News philosophers lack something of the depth of Hancock, Adams and Benjamin Franklin. But the parallels are noteworthy: in its use of marches and street theatre it echoes the tarring-and-feathering mob politics that once governed Boston harbour. So, too, its impressive use of new media. The pamphlets and cartoons of 18th-century New England are now replaced by blogs, cable television and internet radio. Also its religiosity: out of the Boston tea party emerged a "solemn league and covenant", drawing on America's Protestant pre-history and committing its members to collective action against the British. In vogue among modern Tea Party members is the line from the Declaration of Independence: "We mutually pledge to each other our lives, our fortunes, and our sacred honor."

What turned the Boston tea party into the American Revolution was the British response – with the Coercive Acts radicalising opinion across the 13 colonies. Wisely, President Obama has not antagonised his Tea Party opponents; he has chosen instead to give them enough rope to hang themselves.

But with disillusion growing and the November mid-terms looming, his prospects don't look promising. What Obama needs to know is that if he is being set up for the role of Thomas Hutchinson – the last British governor of Massachusetts – in this historical morality play, what remains of the British empire is ready to offer him asylum.

• This article was amended on 19 March 2010 to correct the spelling of George Grenville.

