Butter Knives?

I have 6 butter knives in a case which I thought were EPNS because of the markings’ A.B/EP/NS on the blade. Having closely looked the handles would appear to have a hallmark on them. Is it usual for two types on metal to be used or am I imagining it? The hall mark reads JB/Crown/Lion passant/ f for 5 of them and 1 e. Also there seem to be some numbers around the handle. Are they relevant? Can anyone help, please?

It is not at all unusual to have EPNS blades (or tines for forks) and a sterling ferrule. It keeps costs down and adds a bit of class. There is a practical reason as well, as silver is a relatively soft metal and does not stand up to vigorous use as well as an alloy.

Many thanks for your help.
Marnie Crowder