How substantial are 'substantial' damages?

Newspapers often carry legal corrections stating that they have paid "substantial" damages to a complainant. In many cases the sum is not substantial, but newspapers cannot publish the amount as part of the settlement agreed with the complainant's lawyers.
Readers, however, must be left with the impression there has been a bumper pay-out not realising the paper cannot publish the exact sum.
Leicester Mercury editor Keith Perch on his blog remembers how a former Northcliffe editor, Mike Lowe, got round the problem of being banned from publishing the amount of damages.
Perch writes: "We had published something inaccurate about a local councillor who demanded an apology and damages and a deal was agreed which included such a ban on revealing the amount paid out, but describing it as 'substantial.'
"At the time, we published an item every day called 'word of the day.' This would take a word from an article in the paper and explain what it meant. It was usually Mike's way of explaining gobbledegook and was an interesting little feature.
"On the day that we published the apology and the line about substantial damages, the word of the day was 'substantial' and it was defined simply as: £500!"