Paula Radcliffe may not have delivered the world best performance everyone was forecasting when the 12th IAAF World Half Marathon Championships took place in Vilamoura, Portugal today. But clinching a third world half marathon title in four years, Radcliffe's winning margin of one minute and 27 seconds was the greatest ever achieved in the 12-year history of the championships.

A combination of hot sunshine and a twisting course at the Portugese venue saw Radcliffe drastically slow at about the halfway point, although still running the world-class time of 1:07:35.

For the second time in less than a fortnight, Radcliffe quickly destroyed the hopes of Ethiopia's defending champion Berhane Adere, runner-up in 1:09:02, and the unexpected bronze medallist from Australia, Benita Johnson, who ran 1:09:26.

Unsurprisingly the previous greatest winning margin was when the marathon world record-holder won on home territory, speeding to a 49-second advantage when claiming her second crown two years ago in Bristol.

Having less than a fortnight earlier ran 1:05:40 on the slightly downhill Great North Run course on Tyneside, it was genuinely believed Radcliffe could threaten Elana Meyer's four-year-old legal world best of 1:06:44.

Beforehand that was a consideration, and with the the year drawing to an end, Radcliffe would have liked to be named as the inaugural world record-holder when the IAAF recognise the event for that status next January.

From the beginning, the world best seemed to be on the cards. Radcliffe after less than two minutes was forging ahead and until an unexpected burn-out before the 15km marker, it seemed Meyer's mark set in Tokyo was destined for the dust bin.

But the scorching Algarve weather, with temperatures rising rapidly from 22C after the start, seriously blunted any ambitions Radcliffe may have had in that direction.

Radcliffe, cheered by around a thousand British tourists, said: "It was a very tough race and I was surprised everyone dropped back so quickly.

"The support was fantastic but I knew at 10km with the conditions being what they were, the record was not going to happen."

Radcliffe still produced another blistering performance which, before five kilometres, hushed the gold medal ambitions of every one of her global rivals.

Her sixth road race victory of the year saw arch-rivals led by Adere and Susan Chepkemei - the Kenyan eventually blew up and finished eighth - chasing her shadow by nine seconds after the first five kilometres.

Radcliffe is human but even with a 36-second lead and on record schedule after 10km, she knew world record ambitions would have to wait for another occasion. "I realised at that point I had won the race."

Despite her positive approach, the effort was seriously hurting. Radcliffe admitted: "People are thinking of the expectations of a world record every time I run.

"Even I am, and I thought of that before the race. But there were too many twists and turns that slowed you down.

"It was not a course to run a record. But I showed I could still run in the heat even if not as fast as I have done in the past.

"I decided there was no point in killing myself but I picked it up in the last 5km again."

With the team medals being decided on the aggregate time score of the the first three finishers, Radcliffe also knew her own contribution could directly influence their finishing total.

"I was running into direct sunlight, but I kept running fast because I knew the team event was still very important," she said.

Despite her efforts, the British team only managed fifth position as Russia claimed a surprise victory ahead of Japan and Romania. Surprisingly, none of the normally superior African nations made it on to the team podium.

The future racing programme for Radcliffe still remains uncertain. But she admitted running a marathon before Christmas is doubtful.

"It's not looking likely I will do Athens or the New York Marathon," said Radcliffe, suggesting a leg of the Ekiden Relay in Japan next month is the preferred choice.