Being forced to move back to dublin to work from the office 4 out of 5 days.

Just quit, if you are important enough you will be accommodated, if you aren't then you never were

Have you tried to discuss it with your manager and see if you can keep the same arrangement? It's a nuclear option, but if they do refuse you could point out that their current policy is discrimination. If that falls on deaf ears you could then consider taking a case against them.

How is it discrimination?

What did they say when you discussed it? Outright refusal or what?

There's no discrimination. Where is your "home" written in your contract?

edit: meant "home office " place of employment.

If people with kids are getting favourable treatment over those that don’t I guess?

Find another job, either local or one that might accommodate you.

Under the family status ground. You can't treat people differently because of their family status. If they are willing to let someone work from home because they have kids and then they can't refuse it for people who don't have kids.

Yes. Family status is one of the nine grounds for discrimination. You can not be treated differently because of your family status. Single people and people with no children are covered by that as well.

It isn't. Its an example of offering family friendly policies to those that might be under particular pressure with dependents and need a little more flexibility.

Choosing to leave the City during the pandemic on a finger-crossed basis, that compulsory office working may never return, is just an example of a gamble that didn't pay off.

Most contracts, certainly any I've ever had, contain a clause to the effect that 'the employee shall live within a reasonable distance of their assigned place of work, such that they may render regular and efficient service'.

This is standard stuff to protect the employer, in the event of location moves, change management issues etc.

The reality is, it is not discrimination, its just a policy that inconveniences the OP.

On the bright side, its a sellers market, go get a role which contracts working from home and be happy.

It is. But the best thing the OP should do is contact a employment solicitor and get proper legal advice if he feels it is worth pursuing.