Check valve need with Fluidmaster Pro45B fill valve?

[Possom]

The Fluidmaster Pro45B brass shank fill valve has an anti-siphon / backflow design which prevents contamination (according to adverts).

Is this sufficient, or does a double check valve additionally have to be added to the 15mm supply pipe? Thanks.

 

[Hot&Cold]

No check valve is required when the fill valve is fitted correctly or on domestic installations.

Why would consider a check valve ?

 

[Possom]

Why would consider a check valve ?

No reason in particular, just wanted to check. It is for a domestic installation.