BRITAIN&rsquo;S Jenson Button finally clinched his maiden world championship yesterday in Brazil before admitting he never quite believed he would reach the very top.<br /><br />The Brawn GP driver battled from 14th on the grid to finish a highly creditable fifth at Interlagos, while team-mate and nearest rival Rubens Barrichello slipped from pole to eighth.<br /><br />It was enough to secure Button the title with one race to spare and complete a remarkable season for the 29-year-old and his team, both of whose futures were hanging by a thread less than a year ago.<br /><br />Long written off as an also-ran, Button has emphatically answered his critics by succeeding compatriot Lewis Hamilton and becoming the 10th British champion in the sport&rsquo;s history.<br /><br />But even in his moment of triumph he admitted doubting it would ever happen, saying: &ldquo;Twenty-one years ago, I jumped in a car. I never expected to be world champion in F1. You think racing drivers are born different to you but I&rsquo;ve done it today.&rdquo;<br /><br />Button flew off the grid earlier in the season, winning six of the first seven races, but trundled over the line in the end as Barrichello and the Red Bull pair of Sebastian Vettel and Mark Webber chipped away at his lead. However he did not let that temper his joy.<br /><br />&ldquo;I feel ecstatic,&rdquo; he added. &ldquo;It&rsquo;s great to be sat here as world champion and I personally think I thoroughly deserve it. I am it. I am a world champion and I&rsquo;m going to keep saying it, especially after a race that for me was the best I&rsquo;ve driven in my life.&rdquo;<br /><br />Prime Minister Gordon Brown sent the Englishman a congratulatory message that read: &ldquo;I want to send my warmest congratulations to Jenson Button. We can be proud that Jenson is the 10th British driver to win the title.&rdquo;<br /><br />Webber won an action packed race ahead of BMW Sauber&rsquo;s Robert Kubica and Hamilton. And it was a double celebration for Brawn GP, as the team formed from the ashes of Honda scooped the constructors&rsquo; title in their first year.<br /><br />&ldquo;It&rsquo;s still got to sink in,&rdquo; said boss Ross Brawn. &ldquo;It&rsquo;s very special. Today he had a great race; he knew what he had to do.&rdquo;<br /><br />Button&rsquo;s team-mate Barrichello added: &ldquo;I&rsquo;m pleased for Jenson as a friend and as a great champion and if I didn&rsquo;t win, he should have won it, so well done to him.&rdquo;