Christine Ohuruogu completed a comeback trail pitted with protests and problems by claiming Great Britain’s first gold medal at the World Athletics Championships in Japan yesterday and then pleaded with the British Olympic Association (BOA) to lift her life ban.

The 23-year-old Londoner completed a one-year suspension for missing three out-of-competition drugs tests only 24 days ago and arrived here ring-rusty and burdened by controversy. But she won a breathtaking final of the 400 metres by coming from fourth off the final bend to set a personal best of 49.61sec. Her teammate, Nicola Sanders, the European indoor champion, was second in 49.65, another personal best, to give Britain their first one-two at a World Championships since Colin Jackson and Tony Jarrett in the 110 metres hurdles in 1993.

Barely an hour after the race, Gordon Brown, the Prime Minister, sent Ohuruogu and Sanders a fax that suggested he would support a lifting of the ban. “You have made the whole of Britain proud and I now hope you can go on to win gold together in the relay,” he wrote.

Ohuruogu’s story is one of sport’s most dramatic. She has been forced to take a part-time job at Newham Council to make ends meet after running up a £23,000 legal bill, had six weeks on crutches last year after two Achilles operations and despite completing a 12-month suspension imposed by UK Athletics (UKA) is still barred from competing at the Olympics under the rules of the BOA, which automatically bans drugs offenders for life.

“Right now I don’t know what’s happening with the Olympic appeal and I don’t care,” she said after succumbing to tears on the podium. “I am hoping it will swing my way now – there are precedents for it. I’m No 1 in the world and it would be a shame if I wasn’t in the Olympics [in Beijing] next year. I want to be there.”

Ohuruogu was banned by UKA, acting in accordance with the rules of the International Association of Athletics Federations (IAAF), last August after missing a test at Mile End Stadium. It was her third missed test in 18 months – a school sports day had prompted her to train at Crystal Palace instead. Her coach, Lloyd Cowan, said that the ban had almost destroyed her and Ohuruogu despaired when the Court of Arbitration for Sport (CAS) upheld the decision, despite accepting that there was no evidence of doping. The IAAF itself said the penalty was “harsh”.

Her appeal is likely to be heard by the BOA in late October, but Ohuruogu, a committed Christian, at least has $60,000 (about £30,000), the prize for a world title, to ease her financial problems. “There were very many moments of despair, but when you’ve worked hard and you know you’re an honest person, I believe that God will smile on you and make things work for you in the end,” she said.

Rounding on her detractors, she said that they had helped to motivate her. “I think all the negativity spurred me on,” she said. “I like being challenged, I like people saying I can’t do things. It’s nice to say to people – ‘you got it wrong – ha, ha, ha’.”

Her five brothers and sister watched what they will perceive as her redemption back home in Stratford, just a mile from the site of the Olympic stadium in East London. Ohuruogu was used as a pin-up girl for 2012 but was quickly dropped and shorn of lottery funding after the ban was imposed. Now her manager, Ricky Simms, said invitations to lucrative Golden League meetings in Brussels, Berlin and Zurich next month would follow.

Dave Collins, the UKA performance director, said: “The paperwork has gone in and I would hope the BOA look positively on it [the appeal]. It would be a great shame if Christine did not go to the Olympics. There has been no suggestion whatsoever that this lady was trying to cheat and her fate sharpened a lot of other people’s ideas. It is a tragedy that it had to happen to her.”

Like Ohuruogu, Sanders has had a torrid season because of injuries. Still a hurdler at last year’s Commonwealth Games, she switched to the flat but suffered knee and Achilles injuries this year. “I don’t think I’ll be going back to the hurdles,” she said.