My spouse made almost the same comment about the pension you did when I read this out to them. You're right, 43 years' service would put LW firmly in early retirement age (over 60), and they might have already reached their full pension entitlement before they got fired, depending on where they worked.

If the "honest mistake" was only a pretext, then imho LW needs to talk to an employment lawyer re the possibility of wrongful dismissal.