The pitch process involved more than 20 agencies, which were whittled down to eight, with three making it on to the final roster. Twentysix is the only new agency on the digital roster.
Ian Anderson, business development and corporate director of , said: "This pitch win is an absolute coup. Our creative approach really stole the show as well as our global online marketing credentials.
"Shell is one of the best known brands in the world and we are delighted to be part of their future digital story."