I suspect that the Frederick Knight in 1871 is not yours unless you have proved links with him to the Hazzards.
These are births for Frederick Knight in 1851
June qtr 1851
Knight Frederick
Croydon 4 132
This is probably the Merton one
September qtr 1851
Knight Frederick
Farnham 4 170
This is probably yours
there is also a Frederick Robert with a Farnham registration same qtr/ref