I am US greencard holder with a Sri lankan passport. Do need UK transit visa?

Whether you need a UK transit visa depends on your nationality, the length of your stay in the UK, and whether you'll be leaving the airport during your transit.

Nationality

As a Sri Lankan passport holder, you are required to have a visa to visit the UK, even if you're only transiting through the country.

Length of stay

If you'll be transiting through the UK for less than 24 hours and you won't be leaving the airport, you may be able to do so without a visa. However, if you'll be staying in the UK for longer than 24 hours or if you'll be leaving the airport, you will need a transit visa.

Leaving the airport

If you'll be leaving the airport during your transit, you will need a transit visa regardless of the length of your stay in the UK.

Applying for a transit visa

You can apply for a UK transit visa online. The application fee is £34. You will need to provide the following documents with your application:

* Your passport

* A completed visa application form

* A recent passport-style photograph

* Proof of your onward travel

* Proof of sufficient funds to support yourself during your stay in the UK

Processing time

Transit visa applications are usually processed within 15 working days. However, it may take longer if you need to provide additional documents or if there are any delays in processing your application.

Visa validity

Transit visas are valid for up to 24 hours. However, you may be able to extend your visa if you need to stay in the UK for longer.

For more information on UK transit visas, please visit the UK government website.