Thanks to the NGK Registers and Indexes on FamilySearch.org, I think I have identified the dates of birth and baptism for most of Walter and Hester's children - Walter David Peter Doubell, b2
The only child I wasn't able to find a baptism for was Sarah-Ann Miles nee Doubell, c12 - Sarah-Ann Miles, c11
It also looks like we will need to re-number Susan Catherine (c11, born 1870), Sarah-Ann (c12, born c.1873) and Eva (c10, born 1874) as their birth order has now changed.