List of all countries from where people require visas for transit as well are listed below under Direct Airside transit:

Afghanistan, Gambia, Nigeria, Albania, Georgia, Oman, Algeria, Ghana, Pakistan, Angola, Guinea, Peru,  Armenia, Guinea Bissau, Palestinian Authority, Azerbaijan, Guyana, Philippines, Bahrain, Haiti, Qatar, Bangladesh, India, Russia, Belarus, Indonesia, Rwanda, Benin, Iran, Sao Tome & Principe, Bhutan, Iraq, Saudi Arabia, Bosnia-Herzegovina, Ivory Coast, Senegal, Burkina Faso, Jamaica, Serbia, Burma (Myanmar), Jordan, Sierra Leone, Burundi, Kazakhstan, Somalia, Cambodia, Kenya, South Africa, Cameroon, Korea (Dem. People's Rep), Sri Lanka, Cape Verde, Kosovo, Sudan, Central African Republic, Kuwait, Surinam, Chad, Kyrgyzstan, Syria, China, Laos, Tajikistan, Colombia, Lebanon, Tanzania, Comoros, Liberia, Thailand, Congo, Democratic Republic of, Libya, Togo, Congo, Macedonia, Tunisia, Cuba, Madagascar, Turkey, Cyprus, Malawi, Turkmenistan, Djibouti, Mali, Uganda, Dominican Republic, Mauritania, Ukraine, Ecuador, Moldova, United Arab Emirates, Egypt, Mongolia, Uzbekistan, Equatorial Guinea, Montenegro, Vatican City, Eritrea, Morocco, Vietnam, Ethiopia, Mozambique, Yemen, Fiji, Nepal, Zambia, Gabon, Niger, Zimbabwe. Know your visa better.

Countries for which entry clearances cannot be issued by our visa sections or visa application centres overseas:

Australia, Malta, Solomon Islands, Bangladesh, Mozambique, South Africa, Brunei, Namibia, Tanzania, Canada, Nauru, Tonga, Cameroon, Pakistan, Uganda, Fiji, Papua New Guinea, Vanuatu, Guyana, Seychelles, Western Samoa, India, Singapore, Zimbabwe and Honk Kong. Now know better how to apply.

Note: This list does not necessarily contain all of the Commonwealth countries for which British visa offices do not issue visas.