Weir finished first in the men's T54 800 metres final on Saturday night only for a protest over a lanes mix-up by Australia's Kurt Fearnley, the second-placed athlete, to deny him gold.

A rerun was ordered by the International Paralympic Committee jury of appeal, but 12 hours later Fearnley performed a U-turn and the result stood, ending Weir's wait for his first gold in his third Paralympic Games. Chin has not been so fortunate.

The 16-year-old from Deganwy was reclassified after winning silver in the women's F37/38 discus and will return to North Wales with nothing – not even a category in which to compete in the Paralympics.

The medal fiascos overshadowed a day when Britain surpassed the gold medal target laid down by UK Sport when swimmers Eleanor Simmonds and David Roberts – winning his 11th Paralympic title to equal Tanni Grey-Thompson's mark – and wheelchair tennis ace Peter Norfolk won gold to take the tally to 41 and 90 medals in all.

Swimmer Matt Walker and archer John Cavanagh won silver, while Matt Whorwood and Louise Watkin, in the pool, and sprinter John McFall added bronze.

Chin, who was reclassified on the eve of the Games from the F44 category (as a les autres or other) to the F38 category (for those with cerebral palsy), has been denied a medal in her first Games – becoming the third British athlete after Shelly Woods and Weir to be embroiled in a medal mix up.

Chin, who was born with a lower limb impairment, was on course for Britain's first athletics gold before news of Weir's reinstatement broke and China's Mi Na won the discus with a final round world record throw.

The Briton initially won silver but the result was overturned following a ruling by the chief classifier.

The decision was bizarre after Chin's assessment on September 5 while she also competed in the women's F37/38 shot put final, finishing 10th on Thursday.

However, the IPC insisted Chin was "not eligible, not matching the sport class profile" after she "showed significantly different skill sets" in the shot and the discus.

"If she was only a shot putter, then she'd be an F38," said British athletics team manager Tim Jones. Chin was initially assessed in June at the national trials and Britain were assured her F44 categorisation was correct but a subsequent analysis placed her in the F38 class, despite having no previous medical evidence of cerebral palsy.

"It was a surprise," added Jones of the initial reclassification. "Medically, you're saying they've got a disability they weren't aware of."

After Chin's latest setback, Jones hopes for a future resolution. "She's been a failure of the system," added Jones.