Thirteen years ago today, Britons went to the polls on a glorious spring day and gave Tony Blair's Labour Party a stunning, landslide victory. The result was a triumph for Blair, who promised a new, cleaner politics after years of 'Tory sleeze'. The country seemed thrilled at what it had done. 

Labour's huge majority was unprecedented in the modern era. Only one other post-war government had come to office with a landslide – the 1945 Attlee administration. It gave Blair huge moral authority to change Britain and create a new politics. 

At first, the Blair era lived up to those sky-high hopes. Gordon Brown passed interest rate decisions to the Bank of England. Wales and Scotland enjoyed varying degrees of home rule. Blair played a pivotal role in securing the historic Good Friday agreement, paving the way to lasting peace in Northern Ireland. And the national minimum wage was a boost for the lowest paid. In time, the party reversed years of under-investment in the NHS and schools (although many doubted how wisely that money had been spent).

But Labour soon dashed hopes that it would be whiter than white in power. It took a huge donation from the Formula 1 boss Bernie Ecclestone just before scrapping plans to ban tobacco sponsorship of the sport. It abolished hereditary membership of the House of Lords but replaced one form or patronage with another – Tony's cronies, or appointed peers. It turned the government communications service into a spin cycle, with a deeply partisan head of communications (Alastair Campbell) instructing civil servants. That led to the disgraceful hounding of an honourable man, the government scientist Dr David Kelly, who killed himself under the pressure. Trust in Labour never quite recovered after the Kelly affair, even though the party won a further general election in 2005. 

The decision to support American president George W Bush's invasion of Iraq – and to make the case for intervention with a deeply dodgy dossier of claims – was surely the defining moment of the post 1997 Labour era. A million people marched to protest against the war, but to no avail. Blair was determined to support his unlikely friend, regardless of the white lies it took to get parliament to vote for war. 

Labour's years in power were also derailed by the poisonous dispute between its two greatest powers: Blair and Brown. The feud reflects very badly on both men, but Brown has been revealed as the most flawed and destructive influence. He believed he had a god-given right to become prime minister. Eventually, Blair gave in and left Downing Street. Labour made a terrible mistake in anointing Brown as leader, and prime minister, without an election. Enough people inside and outside the party warned that Brown would be a disastrous prime minister. But Labour was too cowed by Brown's bullying tactics to hold a contest. And the credit crunch and recession destroyed Brown's greatest claim to the top job: his management of the economy for 10 years. He deserves some credit for steering Britain towards economic recovery, but as the Tories found in 1997, voters don't show gratitude to governments that clear up their own car crash. 

Brown's death bed conversion to electoral reform reveals his true colours. Labour had a golden opportunity to introduce a fairer voting system. Its 1997 landslide made reform possible but unlikely – the party should have known that the electoral cycle would run its course. Labour and the Liberal Democrats are natural allies, whatever the tribalists in both parties might think. Yet the first past the post system gave the Tories decades of power from a minority of votes. Labour's failure to act until its dying days in power may have given David Cameron the same advantage. 

All governments and political careers end in failure. But it's a tragedy that the high hopes of 1 May 1997 have been dashed in such spectacular fashion that Labour could end up in third place in the polls. Tony Blair and Gordon Brown should be ashamed.