Chronologically Challenged

I’m reading a book about the works of William Heath Robinson by one Susan Grange, who keeps going on about the Art Nouveau style opening up new ways of doing things in an artistic world on the brink of a new millennium.
    A bit premature if Mr. Robinson died in 1944, over half a century before his millennium ended. Like Tony Blair, Ms Grange doesn’t seem to get that the 19th and 20 centuries both belong to the 2nd millennium and the third didn’t start until January 1st, 2001.