One Quatro brand, two websites
Quatro Casino is not one website but two: quatrocasino.co.uk, the UK-facing address, and quatrocasino.com, the international one. Note that the international domain is a .com here rather than a .casino — the principle is the same, but the address-bar tell is even easier to miss. They share a name and styling, and the UK licence covers only one of them.
We checked the UK side against the Gambling Commission's public register on . The .co.uk domain is held under Apollo Entertainment Limited, account 38620 — an active licence covering 27 .co.uk domains across the Casino Rewards network, with no regulatory actions recorded against it. The brand's listed operator is Fresh Horizons Ltd within that same group. For a UK player, the .co.uk site is the one carrying a real complaints route and an approved dispute scheme.
The international domain, quatrocasino.com, is regulated by Kahnawake and was not on the UKGC licence when we looked. For a UK player that gap is the whole story — the UK safety net does not follow you onto the .com address. The reliable way to tell which you are on is to read the address bar carefully and run the two-minute licence check before depositing.