yep, but, it's worth noting that the UK pulled out from signing the treaty of Rome in 1957...and the conversation behind the "Merger Treaty" in the 1960s. That brought the ECSC, EEC & Euratom into a single structure, collectively known as the European Communities (EC) which became the EU. 1/2
The main reason the british refused to sign the treaty of Rome in 1957 was because of their british empire. The british wanted to pursue a "one-world" economic system with their empire & commonwealth, where sterling was a central currency. Despite so many leaving the empire around then. 2/2