(sorry - namechanged)
Came across an old schoolfriend yesterday who asked about my DCs.
She asked which school DS has gone to.
When I replied the local grammar, she asked if he was the only white face in the class. 
Not one for confrontation, I replied honestly that there's a fantastic mix throughout the school and he's made some great friends.
I swiftly moved on, but now feel crap that I didn't challenge her attitude.