Exempt medically discharged Commonwealth service people from immigration control

I wish to highlight what I see as a pressing issue affecting Commonwealth servicemen and women who join the UK military. Many Commonwealth citizens like myself join, taking an oath to serve and protect the nation. However, when faced with medical discharge, they may find they have to leave the UK, despite having signed contracts and served honourably. Exemption from UK immigration control ceases when a person is discharged from the armed forces. I believe this can cause significant hardship, depending on the individual's circumstances.