In the weeks after President Mwai Kibaki was elected, tales began to surface of outraged passengers hurling abuse at policemen attempting their usual trick of forcing bus drivers to pay bribes. A few years later, allegations of scams involving hundreds of millions of dollars linked to senior members of government shredded popular faith in Mr Kibaki’s promises to tackle graft.

While Kenya’s government can point to cleaner service delivery in some areas, passports for example, Mr Kibaki has made only limited progress in dismantling a patronage system greased by state funds and perfected under his predecessor, Daniel arap Moi.

“There are areas where things are better. What you don’t have is systematic change,” says Maina Kiai, head of the state-funded Kenyan National Commission on Human Rights. ”The small fish simply take their cue from the top; the key to stopping corruption is going for the bigwigs, the brains.”

Although Kenyan business sentiment has proved remarkably resilient to the infighting and splits characterising Mr Kibaki’s government, perceptions of high corruption worry investors, and prompted the World Bank to delay lending. While obtaining permits for business is now easier in many cases, and bribe-taking by low level officials initially declined under Mr Kibaki, the kind of grand scale corruption that stunted economic growth under Mr Moi has continued on a comparable scale.

The short history of the Kibaki government’s anti-graft measures have unfolded like a spy novel, taking in locations from the spires of Oxford to the panelled inner sanctums of Nairobi’s State House., the short history of the Kibaki government’s anti-graft efforts would be compelling if it was not so depressing.

At first, the new administration’s reforms were taken seriously by Kenyans and donors. Among a raft of measures, the government investigated the infamous Goldenberg scandal, a bogus gold and diamond export scheme which cost the taxpayer $1bn under Mr Moi.

The Kenya Anti-Corruption Commission (KACC) was established, while Mr Kibaki appointed John Githongo, the respected former head of Transparency International in Kenya, as its chief anti-corruption tsar. Within a few years, Mr Githongo had quit in frustration, moving into self-imposed exile at St Anthony’s College Oxford where he leaked documents implicating ministers in the new administration’s answer to Goldenberg: a saga known as “Anglo Leasing”.

Huge amounts of money were handed to phantom companies through dubious purchases of everything from police helicopters to forensic labs. The various fraudulent contracts were worth more than $700m. Such rackets may not only affect Kenya. Donors are increasingly concerned that international criminal networks involved in corrupt deals will expose the country to further infiltration by drug traffickers, money launderers and perhaps terrorists.

“The mega-corruption today is a different animal: it’s still big, but it’s changed in nature – corruption has become internationalised,” says Robert Shaw of Transparency International. “It has bigger, thicker tentacles, it’s almost beyond a government’s control.”

The problem, activists say, is that Mr Kibaki has chosen to maintain members of government he needs to back his expected re-election bid this year, however tainted their reputations. “They are siphoning millions and millions off the treasury because they think they can get away with it,” says a Western diplomat, referring to members of Mr Kibaki’s cabinet. “It’s quite obvious that the president, for political reasons, is not going to do anything.”

There was a moment in early 2006, when the climate seemed to be changing. Kenyan ministers started doing something new – quitting when their names came up in connection with corruption scandals. George Saitoti, education minister, resigned when he was named in the Goldenberg investigation, while Kiraitu Murungi, energy minister and David Mwiraria, finance minister, stepped down when their names were linked to Anglo Leasing. Allegations over Anglo Leasing had already forced Mr Kibaki to demote a key ally, Chris Murungaru, from security to the transport portfolio, and he was later dropped from the cabinet altogether. Britain even barred Murungaru from entering the country, a move the ex-minister’s lawyers contested in the High Court in London. But by the end of 2006, Mr Kibaki had reinstated two of the ministers, a move that upset donors, anti-corruption campaigners and many Kenyans.

Speaking a week after the pair returned to the cabinet, US ambassador Michael Ranneberger said the government should bring those guilty of corruption to book, no matter what their position. “Corruption creates a negative perception of Kenya both at home and abroad that will linger and persist until decisive action is taken to bring the guilty to justice – no matter what their position or degree of influence may be,” Mr Ranneberger said in a speech to the American Chamber of Commerce in Kenya.

All the ministers whose names have surfaced in investigations have denied any wrongdoing. The high court ruled that Mr Saitoti should not be prosecuted over Goldenberg. Separately, the attorney-general decided that there was insufficient evidence to prosecute Mr Murungi or Mr Mwiraria. While convictions of high-level officials, long conspicuous by their absence, would go a long way to establishing the government’s anti-graft credentials, there are some more modest but still encouraging signs that corruption is being tackled..

An increasingly aggressive press has eroded the culture of impunity among lower-level officials, while the KACC has conducted useful investigations at the town council or state-owned company level, according to Transparency International. Voters, who turfed out a sitting government for the first time since independence in December, 2002, are also less likely to be impressed by candidates handing out cash in return for ballots this time around.

But for Mr Githongo, the man identified most clearly in the public mind with the fight against the wholesaleplundering of public money, little has changed. “Tragically, the impunity that many Kenyans – including myself – believed to be a thing of the past after the last election is still alive and with us five years later,” he said in a statement issued in January. “What serious actions have been taken to solve this crime against the Kenyan people?” Mr Kibaki still has until voting day to answer.