and a note in the Flamstead Church Records of another Walter
St Leonards
Walter Robinson was baptised 20 November 1898, parents were Walter & Maria Ellen of Flamstead
I have a suspicion that it's the same Walter but dad's name is wrong on the christening record and mother's name is wrong on the 1901 census

There doesn't seem to be another Walter born Flamstead on the 1901 census and tracing the above family back to 1891, this is what I find:
1891RG12/1125 54 19
Flamstead, Ivy Cottage
3 rooms occupiedMaria E Robinson, head, mar, 23, Straw Plait Sewer, b. Flamstead
Ernest R, son, 1, b. do.
(there isn't a birth for a Ralph, but there is one for an Ernest Ralph in Hemel Hempstead 1890)
Also, in 1911, the family seem to be Ernest, Ellen, Hugh, Walter and Vernon.
Marriage Maria Ellen Bone to Ernest James Robinson Dec 1889 Hemel Hempstead.