[https://find-and-update.company-information.service.gov.uk/c...]
Interestingly, they're overdue on their bill with Companies House it looks like. Oops.
Lots of entities in Delaware named Twitter Inc. (3) plus what might be a holding company or two. Hard to tell without more digging.
[https://icis.corp.delaware.gov/eCorp/EntitySearch/NameSearch...]