My mother will be visiting me here in the US shortly and will be staying with me for a couple of months. After her visit here, she would like to travel directly to the UK to visit some relatives there. She is a citizen of a country that does not allow visa-free access to the UK, and would thus require a tourist visa to enter the country.
She wants to know if it would be possible for her to apply for a UK Tourist Visa while she is here in the US on a B visa, or if you are required to be a resident of the US in order to apply for a UK visa here.
Another complication to this is that she has currently already initiated an application process to obtain a UK visa in her home country, but it is looking unlikely that she will obtain her visa before she flies to the US, so she may have to void the previous application and start the application process all over again while she is here.