Litebulbs,
The disciplinary process was agreed jointly between BA and Unite. The fact that 20 staff have been sacked as a result of the process is neither here nor there. You cannot have a mutually agreed procedure that is immediately subject to external arbitration as soon as the results don't go the way you want.
If any of the sacked or otherwise disciplined people has a grievance about their handling then they and their union should take legal action under unfair dismissal legislation. The fact that the union is deciding not to persue this course is in itself interesting. There should be no way that the disciplinary process should be part of any sort of block trade off.