From Beijing to London, transiting through Madrid, Spain, T1 landing and T4S departure, do I need a visa?

A visa will likely be required, the UK is not in the Schengen area. Transiting in the Schengen area and not in the same terminal. It is recommended to consult the embassy, ​​their answers are more reliable.

In fact, all airports in Europe have two channels. One is flying from Europe to Europe, you don't need to go through the immigration department, you can go directly to the luggage hall to pick up your luggage. Overseas, countries outside the European Union are another entry channel, and they have to go through the immigration department. I think you need a transit visa. Is the luggage direct? You need to call the airline company or the ticket agent. If the luggage arrives directly, it may or may not be necessary. Let’s make sure first, during the special period of the epidemic, it is not necessarily difficult to be deliberately embarrassing. A transit visa is recommended.