Dwain Chambers blew Britain's final chance of gold medal glory as their injury-hit and ill-starred ninth World Championships ended on Sunday night.

Even Chambers admitted it should have been gold as the 4x100metres relay quartet had to settle for silver behind a supposedly vulnerable American outfit.

But Hayley Tullett's display of Welsh grit to take an unexpected 1500m bronze ensured Britain doubled their medal tally to four.

That was two more than Edmonton two years ago but this time there was no gold, emulating the historic drought of Athens in 1997 and leaving Britain a lowly 26th on the medal table.

"It should have been gold but I will accept silver," said Chambers, the European champion, who was left distraught after finishing fourth in the individual 100m when expected to take the title.

"I am smiling, I am happy. My confidence is coming back and at least I have got something to take home with me because I didn't want to go home empty-handed like I did from the last World Championships and Olympics."

Chambers was given the luxury of a slight lead for the anchor leg after storming runs from Darren Campbell, the 100m bronze medallist, and Marlon Devonish had overturned a narrow deficit from the opening leg by Christian Malcolm.

But American 200m specialist Joshua Johnson - who has JJ emblazoned on his front teeth - gradually ate into Chambers' lead before snaring him on the line to snatch the gold by just 0.02 seconds in 38.06secs.

"Ideally I would have preferred to be level with the American because I was running blind and did not know where he was whereas the fact I was ahead gave him something to chase," added Chambers.

But this was an American quartet without world record holder Tim Montgomery and former fastest man Maurice Greene, although John Capel and Darvis Patton, the first two in the 200m, were there.

"Greene and Montgomery wouldn't get into that team," said Malcolm, finally rewarded having been part of the quartet who blew their medal chances in the early rounds at the 2001 worlds and Sydney Olympics 12 months earlier.

"You've just seen the future. We will be battling it out for the next five or six years with them."

Campbell, also fourth in the 200m, left the track at the Stade de France with his leg bandaged up as the exertions finally took their toll.

Less than half an hour after the relay silver, Tullett added another sliver of compensation for an otherwise disappointing championships with a battling third place.

The 30-year-old from Swansea, though she now lives in Surrey, was deservedly rewarded for becoming the only Briton to break a lifetime best - shattering it in fact by over a second.

Tullett timed her run to perfection to storm down the home straight and win the battle for bronze in three minutes 59.95 seconds.

Russia's Tatyana Tomashova won in a championship record 3:58.52 with Turkey's Sureyya Ayhan second (3:59.04) while Britain's Jo Pavey finished 10th (4:03.03).

"It was such a shock when I crossed the line I did not know how to react," said Tullett, last year's Commonwealth silver medallist who fell in the Olympic final. "I just didn't know what to do.

"I didn't think I'd seen it correctly and had to wait for it to come up on the screen and see the replay before it sank in.

"I knew it was quite a wide-open final on paper and I wanted to achieve something and it was a case of eyes down and bloody run and keep going for the line."

Elsewhere, there was only further disappointment for Britain before the curtain closed on the championships - especially for javelin thrower Steve Backley whose hopes of finally landing a world title were ended early.

The 34-year-old, twice a silver medallist, missed the cut-off point for the final throws by just 21cm having been well below his best to finish ninth though he insists he will carry on to Athens to try and win the Olympic title next year.

"I felt good in my mind and was up for it from an emotional point of view, but my body did not react in the way I wanted it to," said four-time European champion Backley, whose best effort was 80.13m.

"I was really pushing but my legs just felt heavy and my run-up was jerky rather than smooth. I have not timed it right all year and it's been costing me six or seven metres.

"It's frustrating because I am seeing guys I can beat making throws that are not far in an arena where I usually throw well in."

Russia's Sergey Makarov, who finished second behind Backley at last year's Europeans, won his first world title with his first-round effort of 85.44m.

Britain's men finished fifth in the 4x400m relay while the women faded to sixth having gone into the last leg vying for bronze. Both relays were won by the Americans.