"The sector is very good at the moment with a lot of private interest at auction when we used to get mostly trade buying," says Roddy Newlands, a cataloguer with Bloomsbury Auctions. "More people are now aware that books have collectable value and people have started investing in modern first editions because they can relate to the authors much more than with a literary classic."
Certain books are regarded as blue chips, or "high spots" as they are called in the trade. These are the books in demand in a well-established collectors' market that rise steadily in value year after year.
"Authors such as Graham Greene, Tolkien and James Joyce always have demand - Greene is particularly strong now because his reputation is stronger than ever," explains Christie's head of books, Crispin Jackson.
The tricky bit is spotting who will be popular in a few years' time. If you've bought books from your local bookstore at the usual retail price, you have made a good investment if you've picked the right authors. But if you bought the books on the secondary market, have you wasted your money? The answer appears to be "no" if you've bought wisely.
In 1984, the Book and Magazine Collector magazine listed a copy of Ian Fleming's first James Bond book, Casino Royale, as worth £200 to £400. There was huge surprise in the book market when Casino Royale sold for £1,000 seven or eight years ago.
However, JK Rowling's books aren't worth what they used to be, says Roddy Newlands. "All the first three JK Rowlings did well initially but then people became aware that they were more available than first thought, other than the first book, where only 500 were printed," he says. "Condition is critical but at present a truly mint copy of Philosopher's Stone should make more than £15,000."
It may be worth waiting for the next Harry Potter film if you're selling. A release will usually cause a temporary rise in popularity. That has been the case with Tolkien, and a similar story is expected with CS Lewis when the film version of The Lion, The Witch and the Wardrobe is released.
With first editions, it's generally the author's first title that is valuable as these are produced in much lower quantities while the publisher tests their popularity. The print run on JK Rowling's first book was 500, while her sixth book has an initial run of 10 million - a standard first edition of The Half-Blood Prince is therefore unlikely to ever have investment value.
That said, publishing houses now often produce limited-edition formats and these can be very sought after. GP Taylor's Shadowmancer is rising rapidly in value, for example. The book was published in a limited-edition format and is now worth £2,000.
But it's important for collectors to know what they are looking for. For example, the online auction site eBay lists several copies of the first edition of Shadowmancer for just a few pounds. But the real first edition was published by Mount Publishing in 2002 in a limited run of 2,500. All the eBay examples are actually a special edition produced in 2003 by Faber & Faber, which is not valuable. Research prices using auction catalogues and the website www.abebooks.com.
The other big rule is that, for a book to make big money, it must be in very good condition. If the original came with a dustjacket this must not only be present, but also in fine condition. The dustjackets actually make up to 80 to 90 per cent of the final value of a first edition, so don't even consider investing in an edition without this.
"The Modern First market is always developing," adds Christie's Crispin Jackson, who is keen to try new names in his auctions. "If I was looking to put down a collection I would look at the most popular fiction genres of crime and children's," he says.
"My advice for people looking for the next big-money modern first is to look for books that have got charm and are with small publishing companies."
The downside is that you can spoil your investment simply by reading it. As condition is critical, the less handling it gets the better.
How to spot a first edition
* With older books, if there is no mention of an edition number in the front - it doesn't say 'second impression' or 'third edition' for example - it is likely to be a first edition. More modern titles use a numbering system.
* The numbers 1-10 are printed in the front of the book (and sometimes more if it goes to a large number of reprints). If the books says number one, you've got a first edition.
* Further Information: Bloomsbury Auctions 020 7495 9494, www.bloomsburyauctions.com;
* Christie's: 020 7752 3159, www.christies.com.Reuse content