If it proves impossible to find someone who can attest a passport photo, there is another option. The Passport Office allows UK citizens in this situation to submit a signed declaration that they cannot find a countersignatory, and that the information they give in their application is true to their knowledge. This can eliminate the need for someone to countersign the passport photo, but can extend the time it will take for the application to be processed, which is worth bearing in mind, particularly if the application is urgent.