Thank you Rosie, I have checked those available on FindMyPast, without success. I live in Lancashire so don't have access to the Portsmouth records office.
I have now seen the birth certs for Olive, David and Esther and they all have the same mother. She is Amelia Chandler formerly Rawlings who died in 1917 at the age of 37 in Basingstoke so am happy that this is the right family. These families are all travellers so there have been many name changes and non-marriages along the way!
Thank you all for your massive help as I now have enough to proceed further.
Heather