Obtain a form LS01 from the IPS. You can get the form online, by going to a Regional Passport Office or a police station. Fill the form in, sign it and return it to the IPS at the address on the form. If you get the form online, the IPS will return the completed form to you for your signature. Directions for filling out the form are part of the form. After reporting the loss, you will need to apply for a replacement passport.
Report the loss or theft of your passport to the local police, then to the U.K. Foreign and Commonwealth Office, embassy, consulate or high commission in the country you are in (see Resources). They will supply you with the form LS01 to fill out. You passport will be canceled and new travel documents will be given to you so you can get home.
A replacement passport costs 72 pounds as of July 2009. You submit the standard IPS application form. Get the form from a Post Office branch that offers Passport Check & Send service, request an application form online or call IPS at 0300-222-0000 and ask them to send you the form. You will sign the form and another adult will need to countersign it. Get new passport photos taken to accompany the form. Send the application form, fee, phones and the LS01 (if you haven't already submitted it) to the IPS at the address on the form.