It's a truly hideous incident and a disgusting thing to have happened.
Just as an add-on to the all the (very correct comments) that point out that British Jewish children have no responsibility for the horrors that Palestinian civilians are subjected to...I would extend that out and say that generally, many actual Israeli civilians are not to blame or responsible either. One thing that studying history did for me was show that there is a BIG distinction between the government/military and its civilians, which is why one of the reasons why deliberate attacks on civilians are war crimes under international law. There's an understanding that civilians have an innocence, or level of innocent, in the the whole situation, that the leadership doesn't.
It's totally acceptable to hate the Israeli government, but not acceptable to collectively hate Israeli civilians in general, and unfortunately I think that sometimes gets lost on some people.