Entries are arranged in letter-by-letter alphabetical order tip to the first punctuation in the headword. For example, the entry on Quebec, captureof precedes QuebecAct. We have tried in all cases to use the most appropriate headword, particularly the name by which people were best known. It would be unhelpful to have entered Disraeli under 'Beaconsfield', a name by which he was known for only the last five years of his life, and it would be unreasonable to expect all readers to remember that Lord Melbourne was William Lamb. Where there have been second or third creations of a title, all the holders of that title are arranged together in straightforward alphabetical order for simplicity of reference. Holders of titles created in the Scottish peerage are distinguished by [S] after the headword, for example Melville, George Melville, 1st earl of [S], and similarly [I] denotes titles created in the Irish peerage.
An asterisk within the text indicates a cross-reference to another relevant headword. An item is normally marked with an asterisk only at its first appearance in any entry, and if the reference is merely incidental it has not been marked. We have not asterisked sovereigns after 1066 for England, or after Malcolm II (d. 1034) for Scotland, since they all have entries. 'See also' at the end of an entry indicates that there is another substantial entry with a bearing on the subject. Further reading lists have been confined to longer entries and are limited to key works, partly to save space, and partly because they tend to date rather quickly.
The subject index at the back of the book is intended to reinforce the system of cross-reference and make it easier for readers to identify entries of kindred interest. General entries are listed first, followed by specific examples. The words 'see also' in the index refer the reader to headwords within the index, not within the Companion text itself. The accompanying genealogies are not exhaustive lists of all the members of a dynasty, but are designed to illuminate specific family relationships, for example the important reconciliation of Norman and Saxon interests by the marriage of Henry I to a Saxon princess.