If you have a relative or ancestor who was born overseas, but was still classed as a British citizen at the time of the birth, then it is quite possible that the British Consul or the UK High Commission in the relevant jurisdiction would have been notified of the birth, allowing you to find their record within the GRO's Consular indices.
When you search these records, your search results will be in the form of a list of individual names. This means you should be able to tell if your ancestor is in the list just by viewing their name - although we always advise you to double check the original image, especially the volume and page numbers, before you order any certificates.
Please bear in mind the following information when searching these records: