Sickert is multi-lingual from childhood. German was his native language. French he was speaking in Dieppe, France at five years. English by ten. Others? I don't know but suspect some knowledge but perhaps not fluent. The consequence of multi-lingual is the play on words. Sickert as a boy growing up in London where he lived from age 10, memorized much of Shakespeare and forced his siblings and friends to act in Shakespearean plays he put on as a child. All the word play and puns in Shakespeare were known and played with by young Walter. As an adult Sickert could recite long passages from speeches by Shakespeare.
Sickert's mother loved music and sang in the house when they were children. One favorite was: