It looks like Wales and Scotland already have this policy in place. Northern Ireland does not, but I'm not too surprised given that health is devolved to the government of the country and NI didn't have a government for 3 years. I can't tell if that's still the case.

And it's for long-term (more than one year) residents of England, not just citizens.

The headline should read something like "As of today, all residents of England are organ donors unless they opt out" or "Organ donation law in England has changed to opt-out model."

Though it has nearly 85% of the UK's population (and organs).