Travelers may only stay in the United Kingdom for six months.  After that time period has expired, they must apply for permission to stay in the country.  Permanent citizenship is handled through the U.K. Border Agency, which is a department of the British Home Office. 

Residency:

You must live in the United Kingdom for a period of three to five years, depending upon the type of visa.  Citizenship must be applied for no later than 28 days before the end of the residency period. 

There are two residency rules – the three-year rule and the five-year rule. 

Three-Year Rule:

You must have been living in the UK at the beginning of the three-year period, with no more than 270 days of absence in that three years and no more than 90 days in the last of the three years.  You must have the intention to remain in the UK indefinitely and permanently.  Also, during the three-year period, you cannot have been living in the UK illegally.

Five-Year Rule:

You must have been present in the UK for the entire five-year period, with no more than 450 days of absence and no more than 90 days of absence last of the five years.  You also must have had the intention to remain in the UK permanently and indefinitely for a period of at least 12 months prior to applying for citizenship.

Category of Visa:

There are several different types of Visa holders, each having a different application for citizenship. 

These are as follows:

Tier 1:  General (Highly Skilled Migrants); Entrepreneurs; Investors; Post-Study Work

Tier 2:  Sponsored Workers with Work Permits

Tier 3:  Low-Skilled Workers

Tier 4:  Students

Tier 5:  Temporary Workers

Knowledge of the United Kingdom:

People between the ages of 18 and 65 must pass tests on language and knowledge on living in the UK. 

Other Requirements:

To apply for citizenship in the UK you must be of sound mind and good character. 

Expense: 

The fee for a citizenship application is 750 Euros or $1,014.30 in U.S. dollars if the application is done by mail.  The fee for applying in person is 950 Euros or $1,284.78 U.S. dollars.

The British Naturalization process directed under the authority of the Home Office, and receipt of a Certificate of Naturalization is entirely at their discretion. 

Sources:

British Nationality. (2010). Immigration. Migrate UK. Retrieved on February 12, 2011, from  http://www.migrate-uk.com/immigration/british-nationality.php

Karr, R. (n.d.) Immigration Requirements in the UK. ehow. Retrieved on February 12, 2011, from  http://www.ehow.com/facts_4842621_immigration-requirements-uk.html

Currency Converter. (n.d.). True Knowledge. Retrieved on February 12, 2011, from  http://www.trueknowledge.com/q/convert_950_euros_to_dollars