angryblackman - it is not an issue, and has not been in recent memory for the many who have passed through BA from many minority groups. BA would be unlikely to survive without relying on minorities throughout its operation, sitting next to Hounslow as it is.
No numbers are known to anyone outside HR I would imagine, nor would be forthcoming, appropriate or legal to publish. Since positive discrimination is illegal in the UK, you will be recruited on the basis of your abilities alone.