His mother was a Roman Catholic and so he was christened Willibrord, but was known as Willy (and he even used the name Willy Feller on his papers into the 1940s).
Kanyang ina ay isang Katoliko Romano at upang siya ay christened Willibrord, ngunit noon ay kilala bilang Willy (at siya kahit na ginagamit ang pangalan Willy Feller sa kanyang mga papeles sa 1940s).