Don't throw away that phone directory, says Mike Hicks.

Like me, I expect you have noticed that telephone directories are getting smaller, both in print size and in volume. The number of homes in the private section, again, gets less and less, where people, I suppose, are going over to mobile instead of the conventional landline. Does it mean that in the very near future, telephone directories, as we use to know them, will cease to exist? It looks very much that way as they are shrinking fast.

Directories (both before and after the invention of the telephone) have always been a collectable item. For there was a directory sold at Christies in New York in 2008 which made $140,000. Likewise, way back in 1981, a similar directory sold by Sotheby's with a £30-£40 estimate, made £2,800. There are many records of such old directories making high prices, but normally, they have to be exceptionally rare or very early.

One of the earliest local directories was the one published by Whites. Confusingly, there were two Whites, both from Sheffield, and both were publishers.

William White started publishing books in the 1820s, so way before the age of the telephone. In 1836 William White published The Gazetteer and the Directory of Norfolk and the City and County of Norwich. This was a very comprehensive book which is keenly sought after.

I must admit, I have not found out very much about Francis White, who also operated from Sheffield during a similar job. White's Directories, alongside other ones, have proved very useful when researching for families or businesses going back into the 19th century.

Around about this time we had another business directory publisher, and this was Frederick Festus Kelly. Around 1835 he became the Chief Inspector of Letter Carriers for the General Post Office, which had just begun to emerge. He took over the publication of The Post Office London Directory. He then founded Kelly & Co and he and various family members gradually expanded the company, producing directories for counties all over the British Isles, and in many cases putting some of the small local printers out of business. Kelly's Directories are easily spotted, because of their red covers, which normally have advertisements emblazed on them. These are a great source of information and also keenly collected.

Then along came the telephone - and telephone directories. All really keen collectors would love to get their hands on Volume One Number One of the Newhaven Connecticut District Telephone Directory; this was published in 1878; it contained a mere 391 names, but it is worth a fortune today, at least £150,000.

Now, I don't suppose any of our directories today are likely to get into that category for a very long time, but it makes me wonder whether, if you have anybody in the family who has a habit of saving old directories, maybe you should congratulate them and say 'You are doing a good job!'

If you look on the social media sites, you will find Kelly's Directories for sale for anything from £60-£130; with earlier ones, expect to pay a little bit more, and condition is paramount. White's Directories, again, depending upon the year, can cost you between £25 and £150. Do keep them in dry conditions away from damp, and try not to damage the outer cover because these are extremely difficult to get rebound and original condition is always most sought-after.

Mike Hicks runs Stalham Antique Gallery at 29 High Street, Stalham (NR12 9AH). You can contact Mike on 01692 580636 or info@mikehicksantiques.co.uk.