If your search for a British relative has suddenly reached a dead end it could be because they have travelled overseas. These records could be an indication that you need to broaden your search.
Each record is a transcript.
The amount of information listed varies, but the Index to Register of Passport Applications 1851-1903 records usually include the following information about your ancestor:
Date passport was issued
Any observations noted during the application
These records will allow you to discover if your ancestor wished to travel overseas. The original records are held by The National Archives, in series FO 611 - Foreign Office: Chief clerk's department and passport office: passport registers indexes of names.
There are approximately 360,000 men and women recorded on the Index to Register of Passport Applications 1851-1903 register.
Do remember that passports were not obligatory for travel before 1914, but indicated that the bearer could travel “without hindrance” – so your ancestor could still have emigrated without one.