Smith pays the price for an 88p bath plug (and two XXX movies)

One year ago to the day, Jacqui Smith was basking in adulation for a storming speech defending plans to lock up terrorist suspects for 42 days.

So impressed was her initially hostile audience of Labour MPs that Britain's first woman Home Secretary was suddenly mooted as an outside candidate to replace Gordon Brown as Prime Minister.

The theory went that the middle-aged Midland mum with an Aston Villa season ticket and a fondness for caravan holidays would be ideally placed to take on Old Etonian David Cameron.

It was all downhill from there. Today, Ms Smith prepares to leave the Cabinet a figure of scorn and ridicule, forever associated with expenses claims for porn films, a bath plug and nights in her sister's back room.

And for all her street-fighting skills in her Redditch constituency, the chances are that she will be leaving Parliament altogether by next spring.

Her appointment to the Home Office – inheriting Whitehall's most turbulent department – was the biggest shock of Mr Brown's first reshuffle after succeeding Tony Blair.

Ms Smith had always been regarded as a loyal Blairite and was in tears when he made his farewell Commons appearance.

But the new Prime Minister had been impressed by her doughty performance as chief whip and her success in holding on to her marginal constituency in the 2005 election.

Her appointment appeared justified as she reacted calmly and authoritatively to the discovery of two car bombs in London on her first full day in office, followed by an attempted suicide attack in Glasgow the next day.

Ms Smith succeeded in taking her previously dysfunctional department, which had lost responsibility for many functions to the new Ministry of Justice, out of the headlines. Where predecessors David Blunkett, Charles Clarke and John Reid craved the limelight, she was happy to be in the background. She faced controversy over the Government's refusal to fund a promised police pay rise in full, its determination to press ahead with introducing identity cards and mistakes in immigration statistics.

She also rode out a storm over her admission that she would not feel safe walking London's streets at night.

Her biggest challenge came in selling the 42-day lock-up scheme to reluctant backbenchers. The plans scraped through the Commons last summer – with the support of Northern Ireland's Democratic Unionists – but were eventually abandoned in the face of overwhelming resistance in the Lords.

The retreat was barely noticed as crisis gripped Britain's high street banks and the country crashed into recession.

But disaster was at hand for Ms Smith in the form of two damning revelations about her expenses.

First it emerged that she had designated her sister's house in south London, where she stayed during the week, as her main residence, entitling her to claim second home expenses on the family property in Redditch.

She then faced humiliation as details of her claims were leaked, including 88p for a plug, £1,000 for an antique fireplace (and the coal to burn in it) and £704 for a sofa bed.

Humiliatingly, her husband, Richard Timney, who is her constituency secretary, submitted claims of £5 each for watching two X-rated films on satellite television. Friends said she was "mortified", adding that he would be "sleeping on the sofa for a while".

At that moment, she went from slightly colourless machine politician, who once hit back at journalists' claims that she was a "story-free zone", to the butt of comedians' jokes.

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Jacqui Smith's Redditch majority in 2005.