( CNN ) -- After months of speculation , one of Formula One 's worst kept secrets has finally been confirmed . Fernando Alonso , the double world champion who recently left Ferrari , will rejoin McLaren for the 2015 season , which gets underway in March . The Spaniard , who won back-to-back world titles with Renault in 2005 and 2006 , joins the British team after ending his four-year association with Ferrari . He will be partnered by Jenson Button , whose services were retained above Kevin Magnussen , who stays on as a test and reserve driver . Between them , Alonso and Button have won three world titles , 47 grands prix and achieved 147 podium finishes from a combined 500 races . Now 33 , Alonso will be expected to boost McLaren 's fortunes after a season which saw it struggle to match the pace set by the all-conquering Mercedes team . `` Over the past year I have received several offers , some of them really tempting given the current performance of some of the teams that showed interest , '' he said in a statement . `` But , more than a year ago , McLaren-Honda contacted me and asked me to take part , in a very active way , in the return of their partnership -- a partnership that dominated the Formula 1 scene for so long . '' Between 1988 and 1992 , McLaren and Honda won 44 grands prix out of 80 , with Ayrton Senna and Alain Prost winning all but one of the 16 races in one season . `` I still remember , as a kid , the posters in my wardrobe , my toy cars in which I dreamed I would one day emulate Ayrton , and the kart that my father built for my older sister , and that I ended up falling in love with , '' Alonso added . `` That kart had the livery of one of the most legendary partnerships in the history of Formula 1 , McLaren-Honda , the car that Ayrton drove , the same partnership to which I am now honored to join . `` I am joining this project with enormous enthusiasm and determination , knowing that it may require some time to achieve the results we are aiming for , which is no problem for me . '' It remains to be seen whether McLaren 's new engine partnership with Honda returns it to the top of the sport . Alonso previously joined McLaren in 2007 , but left after just one season due to tensions between him and then rookie teammate Lewis Hamilton -- the now Mercedes driver who was crowned 2014 world champion last month . This time around , Alonso will be paired with the vastly experienced Button . The Briton , who won the 2009 drivers ' title with Brawn , has signed a new deal to extend his four-year stay with the team . `` I am extremely excited to be embarking on my 16th year in Formula 1 and my sixth season for McLaren , '' said the 34-year-old , whose future had been heavily debated in recent days . `` Like Fernando , I am certain that McLaren and Honda will achieve great things together , and I feel sure that , working together , all of us will pull incredibly hard to create a brilliantly effective winning team . `` I admired Ayrton Senna enormously , but , for me , it was the exploits of Alain Prost that inspired me most as a boy . 'The best driver lineup ' `` The way he stroked those beautifully brutal red-and-white cars to grand prix wins and world championships was to my mind poetry in motion , and I have tried to emulate his driving style ever since . `` Being a part of new-look McLaren-Honda is a wonderful opportunity for all of us and I am very pleased to have been invited to do my bit . In fact , I am absolutely raring to go . '' `` I am sure ( Fernando and I ) will work extremely well together . '' After plenty of uncertainty over whether Button or Magnussen would be retained for 2015 , McLaren chairman and CEO Ron Dennis is delighted with the pairing of two former world champions . `` I can safely say that we now have by an order of magnitude the best driver lineup of any current Formula 1 team , '' he said . `` We signed Fernando a little ago , but we decided not to announce the fact until we had also re-signed Jenson as his teammate . For many reasons , our negotiations with Jenson took quite a long time . '' The decision to retain Button means Magnussen loses his seat after just one season in the sport . The Dane finished 71 points behind Button in this year 's championship . `` I am very glad that Kevin will remain part of the team , '' said Button . `` He is a very quick driver and a really nice guy . ''
Two - time world champion Alonso rejoins McLaren , the stable he left in 2007 . Alonso will be partnered by Jenson Button , retained above rookie Lewis Hamilton . McLaren chairman Ron Dennis labels the duo ' the best F1 lineup ' of any F1 team . Hamilton will stay on as reserve and test driver .