Everyone has heard of, say, the Irish Fusliliers, the Glorious Glosters, or Royal Scots Greys.
But where are these regiments today? What are they called? And what were they called a hundred years ago? The painful and much-resented rationalisation of the British regiments - which meant amalgamation or simply disbandment - has been going on since the first regiments were raised in the 17th century, according to the perceived needs of the nation in war or peacetime.
But it accelerated in the mid-1950s and the task has now been completed on General Jackson's watch, in 2007.
Anyone trying to follow the name changes of a particular regiment soon gets caught up in and confused by different histories in different books.
By using clear family trees, Gerry Murphy sorts out all the confusion in one indispensable volume.
The appendices alone are invaluable, showing the number of regimental antecedents, honours, colours and insignia.