24 years in job, no contract, prime duties now being outsourced.

You can find this out yourself by requesting a record from the department in Sligo.
Also his revenue.ie record should show prsi contributions for the last 4 years. Given he was doing payroll I would doubt there is anything untoward in this area.
 
Appreciate those suggestions.
 
It is looking likely that his full role as a bookkeeper will be fully outsourced in the coming months.
This is at the heart of it. Presumably he continues to get paid his full wage, notwithstanding the introduction of outsourcing.

Now, therefore, is the time he should assert himself by insisting on a contract/terms of employment and letting it be known that while he might not wish to drag the WRC into the matter, he is being left with no option.

Assuming his salary is at least €600 a week, his statutory redundancy would be about 29000. If the employer seeks his voluntary termination, he’d need to pay considerably more.
 
Assuming his salary is at least €600 a week, his statutory redundancy would be about 29000. If the employer seeks his voluntary termination, he’d need to pay considerably more.
Also worth mentioning that if there have been previous redundancy programs, especially recent ones or any voluntary redundancies relating to the reorganisation/outsourcing then the terms of these may be relevant.
 
This is spot on and he should do exactly this. Rather than second guessing and trying to figure it out for himself, a good employment law solicitor should be able to rule out the dead ends and help him select a strategy for managing this. Note employing a solicitor for a consultation does not equate going to court. It should simply assist him understanding his rights, in particular if he has any under TUPE, and deciding how to manage his way forward. Separately, he and you need to start planning for life after his current job.

This can all be terribly stressful and eat away at the self esteem. I wish you both all the best with it and hopefully he gets a just outcome.