Lookup Bapt. William Sims, Q1 1863, Crayford St Paulinius, to John and Lavinia

[TadlowNewell]

I can find a GRO register entry for William Sims, Son of John Sims and Lavinia Munns dated Q1 1863 (GRO Reference: 1863  M Quarter in DARTFORD  Volume 02A  Page 295, mmn MUNNS)
but I cannot find a baptism entry for him. All his elder brothers and sisters (10 in all) seem to be baptised in St Paulinius Church, Crayford but I cannot find William, yet I feel there must be one.

It could just be a transcription error/omission. Or maybe he just wasn't baptised soon after birth, but a bit later, though I have tried all those sort of tricks... Maybe I am just looking in the wrong place...

I am particularly interested in this because later in life he started reporting different ages, so the date of baptism would be an important extra snippet of evidence. Any help much appreciated.

[Milliepede]

Was he the youngest? 

Is it possible he was the child of an older "sister" but brought up as another son. 

[TadlowNewell]

He was eleventh of eleven. I had not thought of this possibility, though I should have done so. However, I think it is unlikely because the name MUNNS on the GRO (and hence on the birth certificate which I am too mean to actually buy) tells me it really is Lavinia on the birth certificate, though she would have been 46 at the time which is very old to be giving birth... Hmmm