The Guardian's Amelia Gentleman has won the Orwell journalism prize for a series of articles chronicling what the judges termed "the most difficult places in our society: the Britain of benefit fraudsters, benefit dependents, the carers of our elderly, and institutions for young criminals".

It was the third consecutive year that her work had been shortlisted for the award.

Paying tribute to her writing, the judges – the journalists and academics Brian Cathcart and Ian Hargreaves – said: "An early reader of Down and Out in Paris and London praised George Orwell's 'true picture of conditions which most people ignore and ought not to be allowed to ignore'. The 2012 Orwell prize winner for journalism paints just such pictures for our times. Amelia Gentleman's beautifully crafted examinations of hardship, welfare and justice for the Guardian bring us almost painfully close to subjects that are too often ignored, and they do so with cool, sharp powers of observation."

The Orwell book prize went to Toby Harnden for Dead Men Risen, his account of the "under-equipped and overstretched" Welsh Guards fighting in Afghanistan in 2009.

According to the judges, Harnden's "remarkable book takes us into the hearts and minds of the Welsh Guards in a way that is both compelling and visceral". They added: "It challenges every citizen of this country to examine exactly what we're asking soldiers to do in Afghanistan. And rather than offering easy answers it lets the soldiers speak for themselves."

The blog judges, meanwhile, honoured the Rangers Tax Case blog for its efforts to investigate the financial scandal surrounding the football club, describing it as "a worthy winner which not only proves that independent blogging is as healthy as it ever was, but also offers a mirror in which our times are reflected".