Bit of a long shot but...
Does anyone have access or knowledge of burials in the area?  
If Kenneth G as seen in 1911 and born 1910 and most likely died in 1913 is the older brother (prob born 4 Oct 1910 as per death ref)
- then there may be a burial record or MI for him which may have more info.  It won't have Nicholas G and Dora E on as they were not born until after he died though. 
But - if it was a family plot there may be some leads there from later burials?
Death
Nicholas Glyn Baker
Birth Date:   4 Oct 1916
Death Reg: Newport Sep 1986 vol 28 p 395
Age at Death:   69 
Last known address for Nicholas J Baker (father) from CWGC "Thornbank," Ton Mawr Avenue, Blaenavon, Monmouthshire. This matches earlier census records so that address covers the 1913 period in question. 
Also - did we find a death for the mother Florence Edith, I can't remember? Or even the grandparents Edwin and Grace Baker.  There may be something in their burial info?
Milly