Penton Avenue Sub Post Office is located in Staines, United Kingdom on 4 Penton Avenue. Penton Avenue Sub Post Office is rated 3.3 out of 5 in the category post offices in United Kingdom. At the Post Office our aim is to provide you with the things that are important to you – from your mail to your broadband package, your car insurance to your savings account. Whether you pop into a branch or shop online, you can be sure all your needs will be handled with care. That’s the Post Office promise.