The chip inside the passport contains information about the holder’s face – such as the distances between eyes, nose, mouth and ears. These details are taken from the passport photograph that you supply. They can then be used to identify the passport-holder. The chip also holds the information that is printed on the personal details page of your passport.
This scheme would be useful in preventing the falsification of UK passports even if there is no true biometric matching involved.
If the chip in the passport contained only a digital copy of the passport that the government issued, a forger would need to forge the document and the chip. A forger that "found" a "lost" passport would have to alter the passport with a picture of its new user and find a way to get that new photo onto the chip.
The UK passport chip uses RFID technology. Travelers might want one of these.