As a Jewish person who is integrated into the UK and whose family has contributed to the economy for generations, I personally feel much safer around British or English flags than Palestinian flags.
I have not personally seen "hordes of angry aggressive English people putting flags up", unless it is at a march for Palestine.
From what I see, only a small number of the most extreme far right wing have an issue with people who are of another background.
The majority - from centre through to right wing - will accept anyone of any colour or origin who is prepared to come to the UK legally, integrate into the UK and contribute, accept British law and stand under the UK flag.
I have far more of an issue with people who claim that the British or English flag are racist. Just because a few far right mis-used the England flag doesn't mean everyone should be tarred with the same brush.
Patriotism is uniting, nationalism is divisive. The majority of people flying flags are patriotic. The people calling everyone a racist or fascist for doing so, are being divisive.
(I understand for some in NI flags do have a very different connotation)