Essential Information - Postal Service
Post Offices
Mail can be sent at post offices and by placing them inside the red cylindrical shaped (and square wall mounted) Royal Mail post boxes. 
Stamps can be bought from post offices and many newsagents. Mail can be sent either first or second class. Mail sent first class will reach most destinations within the UK the following day; second class mail within two days of being posted.
For general postal enquiries ring Tel: 0845 722 3344.
Rates
Domestic 1st-class mail is quicker but more expensive (28/42p per letter up to 60/100g) than 2nd class (20/34p). Postcards and letters up to 20g cost a uniform 36p to send anywhere in Europe ; to almost everywhere else, including the Americas and Australasia , it's 47/68p up to 10/20g. Packets and parcels up to 100/200g cost 89p/£1.34 to Europe and £1.17/2-2.13 to everywhere else. They must be taken to the post office for weighing. Airmail letters to the USA or Canada generally take three to five days; to Australia or New Zealand , allow five days to a week.
Poste Restante
Unless you (or the person writing to you) specify otherwise, poste restante mail sent to London ends up at the Trafalgar Square post office (tube Charing Cross), 24-28 William IV St, WC2. It opens 0800 to 2000 Monday to Saturday and 0900 to 2000 on Saturday. Mail will be held for four weeks; ID is required. Amex offices will also hold clients' mail for free.
Postcodes
www.royalmail.co.uk
The London postal code system is a remnant of the First World War and confuses Londoners themselves. The whole city is divided up into districts notated by a letter (or letters) and a number. For example, W1, the Mayfair and Soho postcode, stands for 'West London , district 1'. EC1, on the other hand, stands for East Central London, district 1. The numbers are assigned alphabetically throughout the districts and make little logical sense. However, postcodes are a good way of differentiating London streets that have identical names. For example, Harrow Road exists in E6, E11, NW10, W2, W10 and W9.
Post Office Services
In addition to the normal mail services of sending letters and packages, the following are a few Royal Mail services which you may find useful:
Special Delivery - offers a guaranteed next day delivery by 12.30 to most UK destinations; a signature on delivery is also obtained.
Recorded - provides a certificate of posting as proof that your mail has been posted, and a signature on delivery is also obtained.
Registered - offers a guaranteed next day delivery by 12.30 to most UK destinations; a signature on delivery is also obtained, and compensation for loss or damage is available up to maximum amounts of £500 - £10,000 dependent on whether you use Registered, Registered Plus, or their Consequential Loss service.
Advice on Delivery - this ensures that a signed receipt of delivery is sent back to you when you use either Special Delivery, Recorded or Registered services.
