Rupert Cornwell: An odd couple in the capital city of spies

Out of America: The husband and wife who face trial as suspected Cuban agents seem to be naive romantics, a world away from other moles

Washington is the acknowledged global capital of espionage, and the International Spy Museum, in a newly fashionable area of the capital's downtown, is one of its biggest tourist attractions. And now that reputation is to gain a further boost – and the museum an additional attraction – with the extraordinary case of Kendall and Gwendolyn Myers.

America has produced a rich crop of spy cases over the 15-odd years I've been a correspondent here. There was Aldrich Ames, the CIA counter-intelligence officer and mole who sent at least 10 US agents to their deaths, as well as Harold James Nicholson, a fast-rising CIA station chief, and the FBI special agent and computer expert Robert Hanssen, said by some to have been even more damaging than Ames and who was sentenced to life in prison without parole in 2001.

Usually American spies are in it for the money. True, Hanssen seems to have felt his talents were insufficiently appreciated by his employers and took up espionage in part to prove his point. But he was also well remunerated for his pains. As for Ames, who received $2.7m (£1.6m) from Moscow before his arrest, he was the best-paid spy in all history. Nicholson didn't do too badly by the Russians either – he even sent his son to Russia to discuss "pension" arrangements after completing a 23-year jail term somewhere around 2020.

But the Myerses, on the basis of the known evidence, were different. For one thing they are in their 70s. For another, they allegedly spied not for Russia, or even for Israel (for which the former US navy analyst Jonathan Pollard is serving a life sentence), but for Cuba. The methods they used in an espionage career that lasted almost 30 years were relatively primitive – most notably a shortwave radio and the exchange of shopping trolleys with Cuban agents in a Giant supermarket in affluent north-west Washington.

Gwendolyn Myers had been a passionate opponent of the Vietnam War, who worked on Capitol Hill and as a volunteer on Democratic political campaigns in the turbulent late 1960s and early 1970s. Kendall Myers was a gentleman liberal, a scion of one of Washington's most eminent families who counted Alexander Graham Bell, inventor of the telephone, among his ancestors. An academic specialist in European affairs, he later became an intelligence analyst for the State Department, with a high security clearance.

The turning point came, if arraignment documents are to be believed, in 1978 after he divorced his first wife, when he was invited to Cuba while working as an instructor at the Foreign Service Institute here. The visit left a profound impression, prompting him to write in his diary of "the historic interventions of the US into Cuban affairs, including the systematic and regular murdering of revolutionary leaders".

By then he had met his future second wife, whom he married in 1982. But already, it is charged, they were handing over secret information to Cuba – not, it would seem, out of any desire to become rich, but from disillusion with America's foreign policy and its behaviour in the world.

The Myerses, it is claimed, took no reward other than the grateful thanks of Havana, the cost of their equipment, and the belief they were doing the right thing. According to evidence presented at a bail hearing early this month, they had marked in their calendar a yacht trip to the Caribbean later this year, with no date of return. For prosecutors, that journey sounded all too like a final departure to the country they now considered "home".

If anything, the Myerses come across as naive romantics, utterly different from the greedy, often drunken Ames. A better parallel might be our own ideological spies of yesteryear. Like Philby, Maclean, Burgess and Blunt, Kendall Myers was a product of the establishment. If he crossed over, it was not for financial gain but from a belief, however misguided, that the other side was better.

The Myerses, of course, do not seem to have been in the league of the Cambridge spies. Indeed, they are not facing charges of espionage, but the lesser offences of conspiracy, wire fraud, and being agents of a foreign government – to which they have pleaded not guilty. For now they must be presumed innocent. But the bail hearing judge has already declared that "to put it bluntly, the case against them seems insuperable".

In retrospect, Kendall Myers gave a hint of what he was about in late 2006, in an address at a Washington policy institute, criticising Tony Blair for his slavish support of George Bush over the Iraq war, and declaring that the so-called "special relationship" with Britain was a one-sided sham, in which the US did all the taking and none of the giving.

The speech caused a predictable ruckus in London and Washington. At the time however, we thought it was merely a gaffe – albeit a pretty spectacular one – by a veteran American official who felt he had nothing to lose by delivering a few home truths. In hindsight, the outburst may have been less an assault on Britain than a denunciation of his own country's policies, extending beyond its bullying of Cuba and beyond the widespread distaste in the State Department for the "my way or the highway" policies of one particular president. As Myers himself noted in his diary, even watching US television news was "a radicalising experience".

Although the couple have pleaded not guilty, it would be astonishing if the case came to trial. The government wants to keep classified information under wraps; we may never know just how sensitive was the material the Myerses allegedly provided or whether Cuban intelligence passed it on to other countries hostile to America. As for the accused, co-operation usually offers the best chance of a reduced sentence. Even so, the charges carry a jail term of up to 17 years. A spell in prison probably awaits the Myerses. But one of those Giant supermarket carts can surely look forward to a place of honour at the International Spy Museum.