Zimbabwe Visa
This means that in the event that you intend to go to India via London you aren't going to require a British transit visa. Hong Kong has a streak of entry requirements that apply for all foreigners who desire to put in the HKSAR. Some countries might only provide a single entry, some can only offer you single or multiple entry, and others might just provide multiple entry visas.
Make sure you make the most suitable visa for your travel that's valid for the purpose and length of your stay. None are very likely to arrange a transit visa for you unless you're a customer. In case the traveler seeks layover privileges for purposes other than for transit through the USA, such as to visit friends or participate in sightseeing, the traveler is going to have to qualify for the kind of visa necessary for that objective.