The GCHQ Puzzle Book (2016)

Penguin Books

Explanation of Puzzle Types

There are a couple of puzzles that appear regularly in this book but which need a little explanation. These are called ‘Where?’ and ‘Which?’.


These questions consist of a list of words. Although written in columns for convenience, the words are just one list which should be read from left to right and from top to bottom. The question itself asks you where in the list an additional word should be placed.

The way the puzzle is constructed is that the words in the list can be divided into sets depending on words associated with them, and the way these words are associated. Each set is of the same size and has words associated in a different way, and these associated words are in alphabetical order through the list. Typically there are 7 sets of 8 words, or 8 sets of 7 words, though other arrangements may appear. The additional word belongs in one of the sets, and you have to work out where in the list the associated word fits alphabetically, and hence where the word itself should appear in the list.

An example may help. Here is a sample question:

Where does JACKSON fit in the following list? (Read left to right, top to bottom.)


To solve this you need to find some sets. For example, you might see SPROUTS and PACT and think of BRUSSELS SPROUTS and WARSAW PACT. Brussels and Warsaw are European capitals, so you then look for more words which can be preceded by European capitals. This leads you to:


Note that the associated words, in this case the capital cities, are spread through the list in alphabetical order. They can now act as a guide to other sets.

Next you might notice CORONATION and EAST, and think of soap operas, or you might see NODDING and NANNY and think of farm animals. Filling in these sets gives:


The associated words have here been written above the words in the list for convenience – the sets are:



EASTenders, HOLLYoaks, CROSSroads, BROOKside, CORONATION Street, DOCtors.

Note that each set so far found has 6 members, so there must be 5 sets of 6 words – and JACKSON must belong to one of the missing sets.

Looking at the remaining words, you might notice that HUNT has to be associated with a word that comes before Berlin alphabetically. This might lead you to think of AUNT, which can be formed by changing the first letter. Similarly LAUGHTER could become DAUGHTER in the same way. Other words in this set are RATHER/FATHER, BOTHER/MOTHER, MISTER/SISTER and WON/SON. This gives you six words and six family members, so this set is also complete.

The remaining words are ROBINSON, BUSH, KIRK, KENNEDY, GRANT and of course JACKSON. These look like surnames of famous people, but there needs to be a link more specific than that. If you think of GEORGE W BUSH and JOHN F KENNEDY then you’ll see the link is that these are people known by names including a middle initial. The others in the list are EDWARD G ROBINSON, JAMES T KIRK and RICHARD E GRANT. JACKSON must belong to this group, and indeed SAMUEL L JACKSON fits the pattern. To answer the question, you just need to say where JACKSON would go in the list, based on where SAMUEL fits alphabetically.

The complete list is therefore:


So the answer is that JACKSON fits between BLACK and BROOK.


These questions consist of a list of 55 words, which can be divided into 10 sets, all of different sizes. Put another way there is one set of 10 words, one set of 9 words, one set of 8 words and so on down to one set of two words and one set of just one word. You need to identify the word in the set of one.

The way these questions are constructed is that the words in each set are connected to the size of the set. So the words in the set of ten have some connection with ten, the words in the set of nine have some connection with nine, and so on. Again an example might help – in this case cut down to just sets of sizes 1 to 5.

Which word is in the set of one?


In this case it may be that the names ATHOS, PORTHOS and ARAMIS stand out. These are the THREE Musketeers. You might spot some of the other names are those of stars – ARCTURUS, CANOPUS, PROCYON, RIGEL and SIRIUS. There are five of them, so it’s a FIVE STAR solution!

That leaves:


Four of these have four letters – but more to the point they have IV, the roman numeral for FOUR, in their centres. Of the remaining three words, both HITHER and ON form new words if suffixed by TO (HITHERTO, ONTO), which is a homophone for TWO. So the answer is BRIAN. This is associated with ONE, as a famous BRIAN is BRIAN ENO, and ENO is ONE reversed.

So the 5 sets are:



3 – Three Musketeers: ATHOS, PORTHOS, ARAMIS

2 – *to: HITHERto, LEANto