Button took advantage of an error from McLaren team-mate Lewis Hamilton that proved to be the turning point at a stage when it appeared as if the latter was on course for back-to-back wins.

Instead, it was Button who held his nerve, but with title leader Sebastian Vettel second in his Red Bull the German has increased his lead in the standings to 85 points over team-mate Mark Webber, who was fifth.

After an eventful race that included five pit stops and a drive-through penalty, Hamilton had to settle for fourth behind Fernando Alonso as the Ferrari driver completed the podium.

Vettel led a nervous first lap of the Hungarian Grand Prix as the cars danced across the slippery Hungaroring track.

Due to constant light rain, it meant the race was a wet one for only the second time in the 26-year history of the event.

Even on intermediate rain tyres, it was clear the conditions were tricky, with the cars twitching from side to side on occasion as they fought for grip.

At the start Vettel managed to make a clean getaway in his Red Bull, leaving the McLaren duo of Lewis Hamilton and Button to dice with one another through the opening turns, at one stage touching wheels.

After three laps, however, it was Vettel fractionally ahead of the chasing Hamilton, with Button on his own in third, ahead of Nico Rosberg in his Mercedes who had climbed three places to fourth from seventh.

Michael Schumacher had jumped up four, from ninth to fifth, early on and was running behind his Mercedes team-mate.

However, he eventually lost out on lap two to Ferrari’s Alonso, who had eased past his own team-mate Felipe Massa at the start.

On lap five Vettel made a mistake, running wide going into turn two and so allowing Hamilton to sneak up the inside and take the lead.

The reigning champion and current title leader just managed to return to the track ahead of Button to at least hold onto second.

Two laps later and it was Alonso’s turn for an error, the Spaniard going off track at turn 12, with Massa flying past him to claim fifth.

However, that advantage was soon lost on the following lap as Massa spun through two, the rear of his car clipping a wall, sustaining minor damage to the rear wing and losing four places as he dropped to ninth.

With a dry line appearing it was now a question of who would jump first and switch to slick tyres, with Mark Webber from sixth and Massa doing so at the end of lap 10.

Button, competing in his 200th grands prix, then followed a lap later, and as he exited the pits and rounded turn one, the Briton fought to keep control of his car.

On the following lap Hamilton, Vettel, Alonso and Rosberg all took to the supersoft rubber, with the gap at that stage between the front two 5.4 seconds.

That momentarily handed the lead to Schumacher who held up Hamilton for half a lap before the 26-year-old passed into turn 12.

When Button manoeuvred his way around Vettel on lap 13, McLaren were running one and two, with Vettel dropped to third.

In 13th position, Williams’ Pastor Maldonado was given a drive-through penalty for speeding in the pit lane.

After 16 laps Hamilton led Button by 6.5secs, with Vettel 0.8 further back, followed by Webber, Alonso and Rosberg, with Paul di Resta running a superb seventh in his Force India.

On lap 20, Lotus' Jarno Trulli became the first to retire due to an oil leak.

With the dry line more prevalent, lap times began to tumble, with Hamilton holding an 8.5secs cushion to Button after 22 laps.

Hamilton, however, then started to lose considerable chunks of time to Button, who took 1.4secs out of his lead on lap 24, and was the quickest man on the circuit at that stage.

The following lap, as Nick Heidfeld emerged from the pits after his second stop, the Renault engine appeared to blow, leading to his car catching fire.

Pulling over onto the grass along the pit straight, Heidfeld was forced to make a hasty exit from his cockpit as flames lapped around him.

At the end of that lap Webber and Alonso pitted again, as did Hamilton the following lap, his margin over Button having been slashed to 1.6secs.

Button came in on lap 27, and then Vettel the following lap, the 24-year-old needing to take avoiding action as marshals were towing Heidfeld’s burnt-out car back up the pit exit.

Just prior to that Schumacher joined the list of retirees, reducing the field to 21 runners.

After 30 laps, with all the leaders bar Sauber’s Kamui Kobayashi in sixth having made two stops, Hamilton had again extended his lead to 7.2secs over Button.

The British duo were followed by Vettel, Webber and Alonso, with Di Resta down to ninth.

Having dropped to eighth place Kobayashi finally came in at the end of lap 34, relegating the Japanese driver to 13th, with Di Resta moving up to eighth, 10 seconds behind sixth-placed Massa.

From fifth, but 33 seconds clear of team-mate Massa, Alonso made a third stop, the move clearly designed to help him try and leapfrog fourth-placed Webber.

The tactic appeared sound as Alonso took 3.8secs out of Webber on lap 38, cutting the gap between them to 13 seconds.

Red Bull made their move on lap 39, but too late for the 34-year-old Australian as he finally dropped to fifth.

Hamilton made his third stop after 40 laps, handing over the lead to Button who continued on, although third-placed Vettel took on a fresh set of super-softs after 41 laps.

Button’s lead was only brief as he came in on the end of lap 42, emerging just ahead of Alonso who had climbed to third on strategy with Vettel now fourth.

Alonso’s joy was short-lived, however, as Vettel passed around the outside on the approach to turn one on lap 44 to reclaim third spot.

Four laps later, and with a sprinkling of rain covering the track, Hamilton conjured an error of his own, spinning into turn seven.

Amazingly, Hamilton then performed a donut into the face of the oncoming traffic, including Button who was forced to weave his way around the outside to take the lead, while Adrian Sutil in his Force India had to take to the grass to avoid a collision.

Hamilton then did just enough to hold off Vettel before taking off in pursuit of Button, only for the rain to increase in intensity.

On lap 51 Button then ran wide at turn two, allowing Hamilton to reclaim top spot, only for them to change position again on lap 52.

First Button passed Hamilton along the straight prior to the latter taking his team-mate into turn two before stopping again to take on intermediate tyres at the end of that lap.

After 53 laps Button led by 5.9secs, with Hamilton a further 13.9secs down the road – however, his bid for the win was shot when he was handed a drive-through penalty for forcing Sutil off track.

Clearly having switched to the wrong tyres, Hamilton made another stop – his fifth – to take on the softs, taking his drive-through two laps later and falling into sixth behind Massa and Webber.

With 12 laps remaining, Button led by five seconds to Vettel, with Alonso third, followed by Massa, Webber and Hamilton.

Massa made his fourth stop soon after, dropping behind Webber and Hamilton who then battled it out for fourth place behind the leading trio.

It was a battle Hamilton won on lap 64, taking advantage of back markers to scythe his way past Webber within inches to spare as he pulled out from behind the Red Bull.

Come the conclusion of a captivating race, Button clinched the 11th win of his 200 grands prix career by 3.5secs to Vettel, with Alonso a further 16.2secs in third.

Over the radio a triumphant Button said: “Guys, perfect going into the summer break. Let’s come back and win them all.”

Hamilton was fourth, 48 seconds adrift, followed by Webber and Massa, with Di Resta seventh for his best result in F1 to date.

The Toro Rosso’s of Sebastien Buemi and Jaime Alguersuari were eighth and 10th, with Rosberg sandwiching the duo.

In the standings, Vettel has again increased his lead, this time to 85 points over Webber, with Hamilton 88 down, Alonso 89 adrift and Button exactly 100.