OK Jim, straight answer please.
Is on street grooming by groups mainly a crime of BPs?

Steve,
"these young men are in the gangs they are in at least partly because of racism leading to ghettoisation and social deprivation"

Ghettoisation. BPs tend to live in communities around Mosques, madrasas, Halal suppliers, etc, and because they want to preserve their culture.
I do not think anyone is to blame for that.
It has been stated that these gang members are quite affluent, with their fancy cars, money, alcohol and drugs on tap.