A common advice I hear for travelers is that having more travel visas in your passport will raise your chances to get more travel visas from other countries.
For example, if you have a Schengen and a US visa then this will aid your UK visa application and vice versa.
My question is, do these 3 parties share information?
I traveled to Germany for example in April. Would the UK and US embassies know about my Schengen visa and length of my stay?
If they rely on the physical visa in the passport, would that mean when applying for a UK I may need to submit my old expired passport as well if it has a valid Schengen visa?