your second assumption is false because the idea of race is a relatively recent phenomenon.
If you read any of the old Roman texts, you would not find reference to race rather you would find references to a person's ethnicity. Ethnicity is tied to culture and language.
It is only controversial when you have what is the far right using Mott and Bailey arguments to justify racism.
Again the assumption made by the article is that these are British ethnic minorities who would have a British Accent since they would have lived there. They are not talking about non-British nationals.
I think you're really stretching and trying to find an alternative answer, where the right answer is staring you in the face.
I'm sure this study has accounted for the fact that these Asians students are British Citizens and have spent their entire lives in Britain and also has English as their Primary language.
These Engineering Recruiters have innate bias against ethnic minority students.
The real question would is, How do we combat this?
If you read any of the old Roman texts, you would not find reference to race rather you would find references to a person's ethnicity. Ethnicity is tied to culture and language.
It is only controversial when you have what is the far right using Mott and Bailey arguments to justify racism.