It is unlawful to offer different terms of employment or to treat an employee detrimentally (directly or indirectly) on racial grounds. A claim made within three months of the discrimination can result in an award of unlimited compensation by an industrial tribunal.
You should review your pay and other terms of employment and treatment of employees for any apparently race-related differences. If they exist, the situation will require remedy. In particular, management and supervisory staff should be advised of correct non-discriminatory procedures and conduct.
It is recommended by the Equality and Human Rights Commission (EHRC) that a race equality policy be developed.