When the blunt-speaking official was appointed it was commented that the government was either being very brave or very stupid.

And when, within months of taking up the post, she walked straight into controversy by attacking homeless charities, many critics were quick to assume the latter.

She was quoted as saying many charities were "perpetuating homelessness" by giving free handouts to people on the streets, comments which sparked considerable outrage.

Swift rise

Much of the criticism focused on her age - with critics suggesting after her appointment at 33 that she had had a swift rise to prominence.

But, in the 12 years prior to her appointment, she has gained extensive experience working within the social sector.

She became involved with the homeless early in her career when, as an employee of the former Department of Health and Social Security she dealt with benefit payments to homeless people.

Later she became co-ordinator of the St Mungo Association, managing the provision of services to single, homeless men.

This was followed by a directorship, taking charge of the Homeless Network, co-ordinating services to rough sleepers in central London.

But it was during her time spent as the deputy director of homeless charity Shelter that Ms Casey made her mark.

Ambitious reputation

Joining in 1992, she quickly gained a reputation as an ambitious, pragmatic worker who got results.

According to Shelter spokeswoman Rachel O'Brien, Ms Casey played a key role in re-shaping the charity, pushing through a number of innovations including Shelterline, a 24-hour phone help service.

"She's blunt, she says what she thinks and she shoots from the hip," Ms O'Brien told BBC News Online.