Since 31.12.2020, there have been some changes and depending on your nationality / type of travel document* you hold, you might need an airport transit visa type A. Please visit the European Commission website to find out if you require an airport transit visa.
Should you require a visa, you will need to submit your application at one of the TLScontact Visa Application Centres. To be directed to the TLScontact website to find out all the information you require about appointments, documents, processing time and general process, please click here.
For easy and fast processing of your visa application, the application needs to be submitted at one of the 'Visa Application Centres' (VAC) and not at the embassy. The addresses in London, Edinburgh and Manchester, as well as all other information, can be found here: London; Edinburgh and Manchester.
WARNING: If you are subjected to the Airport Transit Visa obligation, we strongly advise you to apply for that type of visa. More info HERE. Even if you can claim being one of the exceptions, chances are very real you will be refused boarding in the UK. Example; the Visa Code states in Article 3 that those who fall under directive 2004/38 EC "free movement" are not required to have a transit visa. But then the "accompany or join him" criterion of the Directive 2004/38 applies. A carrier will claim to be unable to verify on the spot this fact with certainty when boarding. Nor can they verify the authenticity of for example a marriage certificate. To be well prepared for a trip: one must travel with a visa.
*if you are a holder of either a UK travel document Convention 1951 (blue cover) or a UK travel document Convention 1954 (red cover), you do not require a visa to transit.