For those interested in collecting UK first editions, I recommend breaking the UK books into five subcategories:
The Bodley Head books (1921 - 1925): five novels and one short story collection. These books can be found quite easily without their dust jackets, and prices are generally in the $1,000 - $10,000 range (see the price guide). With a dust jacket, the price would be what I’ll refer to a ‘what the market will bear’ - which could be up to $100,000. Consequently, many individuals strive to acquire the later printings from Bodley Head, done in the 1920s, with dust jackets priced 3/6 (instead of 7/6 on the true firsts). Even these 3/6 jacketed books, if you can find them, can easily command $4,000 - $7,000 based on auction prices as of September 2019. The much more common 2/6 jacketed cheaper editions are far less valuable, and regularly sell for $300 - $800. True firsts, whether with a jacket or not, are solid blue chips that should hold their value. Continued appreciation at the top end of the scale should not be discounted.
Early Collins (1926-1938): The first book published by Collins was The Murder of Roger Ackroyd (1926) and the last of what I’m calling the early Collins period was Appointment With Death (1938). The reasons I’m segregating this into its own group are as follows: dust jacket artwork was creative, attractive and artistic, print runs were still relatively small (by modern standards), and the books were all published prior to the start of World War II. This latter point is significant as Britain established its ‘Paper Salvage’ program in late 1939 to mandate the collection of paper from households to help in the war effort, knowing from World War I access to paper would quickly become a problem. As a result of this it is believed that many dust jackets were taken from books and given for recycling as in the early years the dust jacket was solely there to help sell the book - it wasn’t yet viewed as part of the package, let alone valuable. As the war progressed, the British Records Association (BRA) began educating people on what should be recycled and what shouldn’t. There was a national concern that archival materials and other valuable items were being discarded. To help save paper as the war progressed, Collins also began printing smaller, thinner books and thus with smaller wrappers. This shift in printing size and the shift in tone from the BRA is the likely cause for why the 1938 books and earlier are the hardest Collins books to find with jackets. Consequently, these are the blue chip collectibles post-Bodley Head, and prices reflect that. All of these books are quite easy to obtain without a dust jacket (though condition varies drastically) and unjacketed books have a value of $700 down to $200 over that time period. However, add a correct first edition wrapper and the value ranges from $60,000 down to $5,000 (see 'Price Guide' from top menu). These are all solid blue chip investments when it is the true first with a correct dust jacket, and preferably with the price showing. The long-term potential for price gains is excellent.
Transitional Collins (1939-1941): There are only a few books in this grouping which ranges from Hercule Poirot’s Christmas (1939) up until Evil Under The Sun 1941. They have some attributes similar to the Early Collins books, such as their size and were still impacted to some degree by the Paper Salvage war effort, but the artwork lost its lustre, availability is generally better than the pre-WW II books, and prices are more reasonable. That said, very good jacketed copies will range in value from $4,000 down to $2,000. The long-term potential for an increase in value is very good, with significant scarcity of quality copies and even fewer unrestored jackets showing the original price.
Middle Collins (1941-1949): This grouping starts with N or M (1941) and ends with Crooked House (1949). These books with their jackets are still uncommon in very good or better condition, several still have artwork on the jackets (though simpler), and thus provide some challenge for collectors. For many collectors this Middle Collins period is where the wallet meets its limits and quality is often sacrificed for attainment. Prices range from $1,000 down to $250 during this period. The long-term upside potential of value increase in this grouping is good and quality copies are becoming scarcer, especially those that have complete, unrestored jackets that still show the correct original price.
Late Collins (1950 - 1976): The first of this grouping is A Murder is Announced (1950) and the last is Sleeping Murder (1976). There are other books published since 1976 that are still considered firsts, but Sleeping Murder is generally considered the last of the run as it was published in the year of her death. These books were all printed in large runs as her popularity was large and the UK population was growing significantly. Consequently, there is some value in jacketed copies, but very good copies will still only command prices of $100 down to $25. The long-term upside potential of value increase in this grouping is minimal.