Until now, nationals from these countries only needed a visa if they intended to settle or work in the United Kingdom. Beginning in mid-2009, they will have to apply for a visa, even if they are only visiting the UK for less than six months.
These changes are due to the new Visa Waiver Test, which was introduced by the Government in July of last year. This test was designed in order to tighten border security and reviewed all non-European countries and regions to determine the risk their citizens potentially posed to the United Kingdom by not having to apply for a visa before they travelled.
Originally, eleven countries failed to live up to the new standards, but over the last few months six of them worked closely with the Home Office and the Foreign and Commonwealth Office to improve their passport and border control systems. However, Bolivia, Lesotho, South Africa, Swaziland and Venezuela are not counted among those. Citizens from these five countries will additionally need a transit visa, if they intend to travel to another country via the United Kingdom.