Fits my theory of accident due to neglect. My theory is she popped out to drop the other kids to school and nursery on Wednesday morning leaving him (genuinely sick) at home, and when she got back he was dead. Knowing she could face jail for neglect due to leaving tiny child alone, she concocted the plot. During the wednesday she moved his body, and then kept the other kids out of his room so they would not see he was gone.
I have amended my theory a little to move the disposal from Wednesday night to Wednesday morning to take account of the reported visit to the bungalow, and the fact no CCTV exists for Wednesday night showing a child being carried from the building.