It is strange.
We know Rosalie was living with Walter Worboys from 1911 onwards and their, I assume their, first children born were registered with MEAD as the mother's name. She then marries Walter in 1915 with the name LAWRENCE and the next three children have mother's name recorded as LAWRENCE.
I couldn't find Rosalie in 1901 to see which surname she used. I guess in 1905, if Winifred was her child, she was somewhere near Royston.