It's been a current phrase for as long as I can remember.

The zestier British alternative might be "to get the sack." (I have no idea what the sack is in a literal sense.)

In Ireland there is a technical legal difference.  If you are fired you have legal rights that may be vindicated under the Unfair Dismissals Act and there is no pretense that your old job is gone, it has simply been given to someone else in your company.

Redundancy is where your job disappears either because your firm has gone bust, or because it has changed its business model and the work you formally did s no longer performed by your company.  You are then entitled to Statutory redundancy payments and also, possibly, voluntary redundancy payments agreed by your employer.

An abuse of the system which has become common is where permanent workers are made redundant but their work doesn't actually disappear - it is done by cheaper workers contracted in from another company.  Technically the work is no longer being performed by the original employer and so the redundancy is legally allowed - but it generally leads to industrial disputes unless the redundancy is voluntary and the workers being made redundant have been given better than the minimal statutory redundency terms.

Index of Frank's Diaries