Yes, I've certainly come across it. I haven't mentioned it in my paper, but in fact particularly after 7/7 there was an enormous increase in racially aggravated crimes throughout the city areas where black and Asian populations lived.
Of course the attackers couldn't distinguish a Sikh from a Muslim, so they just attacked them anyway. Over one month there was an increase of something like 1,000 attacks, and in many of the cases the attackers referred to the victim either as a Bin Laden or a Saddam Hussein. The figures have been published by the criminal prosecution service...quite a dramatic increase.