I want to preface here by saying i acknowledge there are extreme and awful views held by a minority. I do not refute that there is antisemitism here in the UK.
Want i want try to say though is this: i can see (now, reading this thread) that there is confusion about why 'average' people in Britain aren't visibly condemning Hamas, while at the same time are willing to visibly be 'anti-Israel'.
I can see why this could lead to bewilderment and a feeling that the reason must be anti-semetism.
My very humble opinion is this (and i apologise if i'm stating the obvious or sounding thick as mince!) i believe that many average people over here think like this:
Hamas = terrorists. A corrupt and awful government/organisation which is in power through corrupt means, and who everybody knows is doing no good for the people of Palestine. Goes without saying they're obviously extremist bastards.
The Israeli government = a legit, supposedly reasonable sane government, voted for by the people of Israel.
We expect no better from Hamas than what we see; murder, torture, kidnapping. However we don't expect to see a legitimate government committing genocide.
I think that's why we don't see anti Hamas parades - it's a sentiment which kind of goes without saying. They're terrorists. They're not going to be displaced by any diplomatic means - waving a flag will do nothing.
'Israel', ie: BN and his policies however are are within a legitimate political framework and can be protested about with a hopeful view to change.
Its what i think anyway.