A peace campaigning grandmother was jailed for not paying a £50 fine despite a controversy over prison overcrowding.
Mrs Percy earned £1.83 in jail
Lindis Percy, 64, served almost half of a seven-day sentence handed out by Harrogate magistrates on Friday.
Last week Home Secretary John Reid wrote to judges asking them to imprison only the most dangerous offenders.
Mrs Percy, of Hull, was originally arrested last year at the Menwith Hill US base, North Yorkshire.
She was fined £50 for trespassing but refused to pay the penalty.
'Little bit mad'
Mrs Percy, who has been jailed several times before for demonstrating outside American bases, said: "I really do think it would have been more imaginative to think of a more creative resolution to this.
"It must have cost a tremendous amount of money.
"I can't help thinking there are people out there who are more deserving of being in prison.
"I think the world has gone a little bit mad."
She added that during her stay at Low Newton prison, in Co Durham, she had read three books and earned £1.83 by doing various tasks.
Mrs Percy has been arrested on dozens of occasions around the UK, including on the gates of Buckingham Palace in 2003.
She also confronted former US president George Bush about his son's foreign policy when he visited the Yorkshire Event Centre last year.
Mr Reid defended his position last week and denied encouraging softer sentences for criminals to ease prison overcrowding.
He said he was merely re-stating existing guidelines and serious offenders should still be locked up.