His full name is Benji Duncan Geoffrey Rigby-Monk. 'You're joking,' Kit said, when I first told him. 'Benji? Not even Benjamin?' Duncan and Geoffrey are his two granddads'names ― both unglamorous and old-dufferish, in Kit's view, and not worth inflicting on a new generation ― and Rigby-Monk is a fusion of Fran's surname and Anton's. 'As far as I'm concerned, he's Benjamin Rigby,' said Kit, after the first time we met him. 'He seems like a decent baby and he deserves a decent name.
Source: wiktionary