DC, no I do not view infant baptism by (for example The Chuch of England) as invalid.
It`s just that in my case I was never baptised as an infant, If I had been, then the Jehovah`s Witness baptism I underwent as an adult, would have been in my opinion, superfluous, to what I believe today.
As it is, I have only ever been "dipped", by the Jehovah`s Witnesses, and at the time I was baptised "In the name of the Father, Son and Holy Spirit", I view that as acceptable. If I had been baptized under the current wording "...........God`s spirit directed organisation", I would not be happy with viewing that as acceptable to me today.
I hope that makes it a bit clearer for you my view.
All the Best
PAul UK