Analysis By Ian Pollock Personal finance reporter, BBC News

Tom Brennan will have to wait to see if he can sue the NatWest

In the end it took three days, and struggled to get away from the issues at the heart of the controversy surrounding charges that many borrowers are calling unfair and illegal.

Rather than a dry legal hearing, it became a dress rehearsal for a trial - as both sides argued over whether it was fair that banks charged customers for running up unauthorised overdrafts.

"We effectively had a mini-trial," Mr Brennan said after the hearing.

"You are not supposed to have a mini-trial, but that is exactly what we did. At least it shows there are arguable issues."

Unfair or not?

The hearing itself was unusual, in that Mr Brennan was asking for permission to pursue NatWest Bank and its overdraft charges in a novel legal fashion.

Specifically, he wanted to sue NatWest for exemplary and aggravated damages, and also for unlawfully damaging him economically and for breaching its duty to him as a customer.

This case will have significant impact beyond the claimant and the defendant Tom Brennan

The key issue is that a full trial would force the bank to justify why it charges quite so much when people go overdrawn without permission - something the bank has refused to do so far.

At the heart of the argument were charges of £28 per month for being in the red without permission, and a further charge of £38 that the bank imposed for every bounced cheque or standing order.

"The charges are unfair because they do not reflect the actual loss to the defendant," said Mr Brennan.

He added that the trial should go to court because it "would have significant impact beyond the claimant and the defendant".

Consumer crusader

That is precisely why NatWest is fighting so hard to defeat the action.

The judge, Peter Simpson, did not appear very keen on the idea either.

He took a dim view that this claim should constitute a test case, and suggested to Mr Brennan that he was starting to look like a consumer crusader rather than someone with a genuine personal claim.

Mr Brennan, who was representing himself in court, battled hard to win him over.

"It is not a question of cash, it is a question of justice," he said.

"Lives are ruined by these kinds of charges - all I seek is some justice."

In fact, he also wanted "reparations for harm caused to me and other people".

Litigant in person

At times Judge Peter Simpson took a critical view of the fact that Mr Brennan was representing himself, a so-called "litigant in person".

I do not accept you are an ordinary litigant in person Judge Peter Simpson

He upbraided Mr Brennan for failing to submit full and proper documentation, and accused him of trying to plead his case by instalments.

"I do not accept you are an ordinary litigant in person," the judge said sternly, referring to the fact that Mr Brennan was a recently qualified lawyer - albeit specialising in another area entirely, planning law.

Speaking outside the court after the third day of argument, Mr Brennan conceded he had had a hard time before the judge.

"It's fair to say it was an uphill struggle," he said.

Expert witnesses

Judge Simpson reserved his most severe grilling for Mr Brennan' request to call two professors as expert witnesses, should the case proceed to trial.

"It is not clear they have the relevant expertise," said the judge in the course of an hour-long argument on that issue.

Should Judge Simpson allow Mr Brennan to proceed and the case go to court, on any of the numerous points he raised, then the eventual case probably would last for many weeks.

That could be very costly for Mr Brennan.

Ben Pilling, NatWest's barrister, pointed out that Mr Brennan "does not have the resources to pursue litigation", and questioned the quality of the evidence that he would be able to put forward on his own.

So far Mr Brennan's efforts have cost him, by his own estimation, more in lost work as a barrister than he has been claiming he is owed by NatWest.

And he reckons the publicity is damaging his developing career as a barrister.