I don't think BA will be choosing who to dismiss, as that certainly is not a fair and transparent. The only way that BA could choose, is to remove a complete grade as redundant.
There are plenty of fair and transparent ways to select people for dismissal. BA are actually required by law to be fair and transparent, and would be required by a tribunal to provide evidence of such. One fair and transparent way to dismiss people is on the basis of absenteeism or disciplinary record. If I was prone to the occasional sickie and had a poor disciplinary record I wouldn't be feeling too comfortable right now.