How to look for records of... Foreign Office correspondence 1906-1919: using the card index

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1. Why use this guide?

This guide explains how to use the Foreign Office card index 1906-1919 (FO 1111).

You will need to use the index to access Foreign Office correspondence from 1906-1919. This correspondence is in a number of different record series (see section 3.2).

For papers after 1920 see our Foreign and Commonwealth correspondence and records research guide.

2. Essential information

Correspondence received by the Foreign Office was numbered and categorised. Each category now has a corresponding National Archives’ record series (see table 2 in Section 3).

To identify relevant records within these categories you need to use the Foreign Office card index (FO 1111). This index is available to download and view online.

There is a different process for using the card index depending on the date you are researching. The method for 1906-1909 differs slightly to the method for 1910-1919. Please note if you are researching 1910 you may need to try both methods as this was the year the registry system changed.

Please note, not all documents mentioned in the card index survive.

3. Understanding codes in the indexes

Each entry in the card index has a country code and a paper number. The card index from 1910-1919 also contains a file number. The codes have to be translated into The National Archives’ modern document references. Please note these documents have not been digitised and will need to be viewed at The National Archives, Kew.

Each country had its own code, composed of a unique stem number (see table i below).

i The country code stem numbers

Stem code Country Stem code Country Stem code Country
1 Abyssinia to 1914;
Africa from 1914
21 Hungary 41 Spain
2 Argentina 22 Italy 42 Sweden
3 Austria 23 Japan 43 Switzerland
4 Belgium and Congo 24 Liberia 44 Turkey
5 Bolivia from 1911 25 Maskat [Muscat] 45 United States of America
6 Brazil 26 Mexico 46 Uruguay
7 Bulgaria 27 Montenegro 47 Venezuela
8 Central America (Guatemala, Honduras, Nicaragua) 28 Morocco 48 Zanzibar
9 Chile 29 Netherlands 49
10 China 30 Norway to 1914
Scandinavia from 1914
50 General (W50N = War Miscellaneous News)
11 Colombia 31 Pacific Islands to 1913 51 America: General from 1912
12 32 Panama and Costa Rica 52 Contract Labour from 1914
13 Crete to 1913 33 Paraguay 53 Albania 1914-1916
14 Cuba 34 Persia 54 Ecuador from 1914
15 Denmark 35 Peru (includes Bolivia to 1910 and Ecuador to 1913 ) 55 Poland from 1918
16 Egypt 36 Portugal 56 Finland from 1918
17 France 37 Roumania [Romania] 57 Siberia from 1918
18 Germany 38 Russia 58 Caucasus from 1918
19 Greece to 1914
Balkans from 1914
39 Serbia to 1914War from 1914. Please note after 1914 this becomes the code for the First World War however you can find some post 1914 Serbia related material within it 59 Baltic State 1919 only
20 Hayti [Haiti] and San Domingo 40 Siam

ii Category codes

Extra numbers or letters were added to indicate which category the papers were placed in. The category corresponds to a particular National Archives record series (see table below).

For example, Germany had 18 for its stem number, so references to Germany in the card index have the following codes:

Code 18 118 218 318 418
Category Political Commercial Consular Treaty Africa to 1913
Series FO 371 FO 368 FO 369 FO 372 FO 367
New codes added in…
1914 1914 1915 1916 1917
Code 1118 18W or W 18 1218 N18 2118
Category Contraband War series in Prisoners News Coal and tonnage
Series FO 382 FO 371 FO 383 FO 395 FO 382

P or Pr with an abbreviated country name denotes the Prize section in FO 372, the Treaty series.

4. Using the card index 1910-1919

For this period it is easier as the card index often tells you the file number.

Step 1 Identify a card index entry of interest

Use advanced search to search FO 1111 by year. Sort you results by reference – this will put them into alphabetical order. Each letter (or letter range) relates to a subject, name or place so chose a record which covers a topic you are interested in. Download the record and identify a card of interest within the record.

Please note, you may have to do some lateral thinking to find your way around the terms used in the subject index. It can be difficult to know how the Foreign Office would have originally categorised the subjects. For example the card below could be categorised under Portugal, Spain or Reformista Party; or in fact under all. Therefore you may need to download multiple records.

Step 2 Note the following information from the card:

  • country code
  • paper number
  • file number

The file number is usually the lowest number, or the number which appears below another number. When the file and paper number are the same, the whole file is relevant.

For example:



Country code Paper numberFile number Year Subject
36 225385 16 Spanish Reformista party visit to Lisbon

Using the tables above you can work out that country code 36 = Political, Portugal FO 371.

As there is only one number in the paper/file number column this means the file and paper number are the same. When there are two, the file number it is always the lower of the two.

Step 4 Search our catalogue

Use the advanced search to search by the country code within the relevant series. Then from your search results choose the document with the right file number range.

In this example:

Search for keyword: ‘code 36’, restrict your search to the year 1916, and search within reference FO 371.

The relevant document is FO 371/2740 as this covers file number 225385.

Step 5: Identify relevant papers within the file.

When you have ordered your document, you will see each volume is arranged in file order number, and each file is then arranged by paper number.

Find your file number (for example 225385) and within that file find your page number.

5. Using the card index 1906-1909

For 1906-1910 the card index does not provide a file number so you will also need to use the general registers of correspondence in FO 566. These FO 566 registers have not been digitised and therefore you cannot view them online. To view these you will need to visit The National Archives or pay for research.

Step 1: Identify a card index entry of interest

Use advanced search to search FO 1111 by year. Sort you results by reference – this will put them into alphabetical order. Each letter or letter range relates to a subject, name or place so chose a record which covers a topic you are interested in. Download the record and identify a card of interest within the record.

Please note, you may have to do some lateral thinking to find your way around the subject index terms used.

Step 2: Convert the country code using the tables above and note down the paper number.

For example:

Country code Paper number Year Subject
17 28288 09 Flight across the channel

From this information and using the code tables in section 3 you can work out:

  • the country code 17 = FO 371, France
  • paper no = 28288

Step 3 You will need to consult the appropriate general register of correspondence in FO 566 to identify the file in which the papers are kept.

Use advanced search to search reference FO 566 by country and date. From your search results, identify the relevant category – diplomatic, consular, commercial, treaty, or Africa.

In this example, it is diplomatic and therefore FO 566/745.

Please note you will need to order these documents.

Step 4: Identify the file number

Within the relevant FO 566 register find the appropriate date. Then look on the left hand page in the column second from left to find the paper number.

Check the number in the ‘kept with’ column on the right. This gives you the file where the paper is now kept.

In this example the numbers are the same therefore 28288 is the file number you need.


Step 5: Convert that file number into a modern National Archives document reference.

Search our catalogue for the country, and year within the relevant series reference- FO 371, FO 367, FO 368, FO 369 or FO 372.

Sort your search results by reference and look for the range of file numbers which covers the file number you identified in Step 4.

In this example, the relevant document is FO 371/668 as it covers files 17645-29484.

6. Cross-references in FO 566 registers

FO 566 register entries often provide cross-references to related material.

Left hand pages of registers refer to incoming correspondence and right hand pages to outgoing correspondence. Entries in black in the ‘forward reference’ column refer to incoming correspondence numerically arranged on the left page. Entries in red usually refer to outgoing correspondence arranged numerically on the right page.

The file number can then be traced to a document reference as in step 2 above.

7. Other useful record series

Further relevant material may be in:

  • FO 370 – Foreign Office Library and the research department
  • FO 366 – Foreign Office Chief Clerk department. This department mainly focused on expenditure issues and therefore covers many topics

These series are not included in the card index.

This also applies to a number of series containing Embassy and Consular archives, Confidential Print and miscellaneous series. Material gathered in cases (bundles of related material) may appear out of sequence in our catalogue. A consolidated index to these cases is available in the reading rooms, Kew.

8. Further reading

Some of the publications below may be available to buy from The National Archives’ bookshop. Alternatively, search The National Archives’ library catalogue to see what is available to consult at Kew.

Michael Roper, The records of the Foreign Office, 1782-1968 (Public Record Office Publications, 2002)

L Atherton, ‘Never complain, never explain’, Records of the Foreign Office and State Paper Office 1500-c1960, Public Record Office Readers’ Guide No7 (PRO publications, 1994)

The records of the Foreign Office, 1782-1939, Public Record Office Handbooks No13 (HMSO, 1969)

Guide reference: Overseas Records Information 13