In the UK, a notary public is required to verify the identity of their clients before notarising any documents. The exact identification documents required may vary depending on the type of document being notarised and the specific policies of the notary public. However, some common types of identification documents that a London notary public may require include:

1. Passport: A valid passport is one of the most commonly accepted forms of identification for notarial purposes. The notary is likely to request to see the original passport.
2. Driving License: A UK driving license is another acceptable form of identification for notarial purposes. The notary may request to see the original driving license.
3. National ID card: A national identity card issued by a recognised government agency may also be accepted as a form of identification.
4. Residence Permit: A residence permit or visa issued by the UK government may be accepted as a form of identification for foreign nationals.
5. Utility Bills: The notary will also request to see a recent utility bill or bank statement as proof of address. Remember this will need to be less than 3 months old.

It is always best to check with the specific notary public in advance to confirm the exact identification documents that will be required for your specific case. This will help to ensure that you have all the necessary documentation ready before your appointment and can avoid any delays or complications.