The function of a Notary Public in the United Kingdom (UK) is to provide authentication, verification, and certification services for various legal and commercial documents. Notaries Public in the UK hold an important role in the legal system, ensuring the validity and integrity of documents and transactions. Here are the key functions performed by a Notary Public in the UK:

1. Document Authentication: Notaries Public are responsible for verifying the authenticity of documents and ensuring they comply with legal requirements. They confirm the identity of signatories and witness the signing of important legal documents such as contracts, powers of attorney, affidavits, statutory declarations, and wills. By adding their signature, seal, and official stamp, Notaries Public authenticate the documents and certify their legitimacy.
   
2. Witnessing Signatures: Notaries Public are authorised to witness signatures on documents. They verify the identity of the signatories and ensure that they are acting willingly and with full understanding of the documents they are signing. This witnessing function adds an extra level of assurance to the validity and enforceability of the documents in question.
   
3. Administering Oaths and Affirmations: Notaries Public have the power to administer oaths and affirmations. They can help individuals make sworn statements or affirmations in legal matters where such statements are required, such as in affidavits or statutory declarations. Notaries ensure that the person making the statement fully understands its content and consequences before they administer the oath or affirmation.
   
4. Certifying Copies: Notaries Public can certify copies of original documents. When individuals or organisations require certified copies of important records, such as birth certificates, passports, or academic transcripts, Notaries Public can verify that the copies are true replicas of the originals. This certification provides assurance to the recipient that the copies are accurate and reliable.
   
5. International Transactions and Notarisation: Notaries Public in the UK often play a crucial role in facilitating international transactions. They can notarise documents intended for use in foreign jurisdictions, ensuring their acceptance and recognition in those countries. Notaries may authenticate documents for international business transactions, immigration purposes, or when dealing with foreign legal systems.
   

It is important to note that Notaries Public in the UK are independent legal professionals appointed by the Court of Faculties. They are subject to strict regulations, ethical standards, and professional obligations to maintain the integrity and impartiality of their services. The function of a Notary Public is to provide confidence and assurance in the authenticity and validity of legal documents, playing a vital role in the legal system and commercial transactions in the UK.