He is suing the London firm Peter Carter-Ruck & Partners after paying both sides' costs when the jury awarded him pounds 50,000 - an amount the Sun had paid into court in an attempt to settle the claim and avert a trial. Costs swallowed the pounds 50,000 he won and left him a six-figure bill as well.
Nigel Tait, a partner in the firm, said: "He is alleging he wasn't given the right advice about payments into court. After the trial he was awarded his costs by the judge and wrote a very appreciative letter to Mr Carter- Ruck thanking him for all he had done. But the Court of Appeal interfered over the judge's order on costs. This is highly unusual but over the years the Court of Appeal has been moving steadily to reduce payments on libel."
The new case, scheduled for June, will draw attention to payment into court, used to encourage an out-of-court settlement. A plaintiff can accept the money or carry on to trial to win more. But if the eventual award is the same or less, the plaintiff must pay both sides' costs from the date of the payment into court, including for the trial.
Had Mr Roache been awarded pounds 50,001, the paper would have had to pay his costs and its own. The Sun said in a statement at the time: "Mr Roache has learned the first lesson of libel, which is that if you don't like losing, don't play the game. He could have had pounds 50,000 and a full apology ..."
Mr Roache, 65, looked likely to escape the costs at first when a High Court judge ruled that he was justified in pressing on to trial to seek an injunction banning the Sun from repeating the libel. But the Court of Appeal disagreed, saying he could have had an undertaking not to repeat the libel had he accepted the settlement.
Lord Justice Stuart-Smith said a pre-trial payment into court was "a most useful weapon in the hands of a defendant faced with a greedy plaintiff who is making unreasonable demands for damages". The then Master of the Rolls, Sir Thomas Bingham, said Mr Roache had gone ahead "because he wanted to win a larger sum from the jury than the defendants had offered".