Yeah, that seems dubious to me. Among the public here in Britain it's somewhat popular but not a majority, with far lower popularity among people who understand how the sausage is made. Here's somebody who has put quite a lot of thought into this explaining why it's a bad idea from a purely practical standpoint: https://www.youtube.com/watch?v=_DrsVhzbLzU

The woman defending the Death Penalty in that clip is Priti Patel, a Tory MP who was until recently in their Shadow Cabinet. You'd hope she can do better, but judging from her subsequent comments she still doesn't get it.

Now, in the UK most people with a life sentence will (after quite some time) be eligible for parole. Historically it was possible for politicians to block this, but of course the consequence is that if a particularly notorious criminal is scheduled to be paroled, politicians are under pressure to prevent that, while a criminal who didn't attract much public interest leaves on schedule - that's manifestly unfair and a European court told the Brits they can't do that, so eventually the UK's Supreme Court decided there needed to a specific rule, identify a category of people who won't be paroled, and the category they decided on was people who have been convicted of at least two separately conceived murders.

Several European countries have no life sentences. Breivik for example got 21 years, and since he's still an avowed Nazi who wants to kill more people, and will likely still be an avowed Nazi when his sentence ends, they will just hold him until he stops being a Nazi or he dies. No additional sentence needed.

[Edited: Priti left her Shadow role a few weeks ago]

What's the motivation for keeping Breivik locked up? I have trouble believing it is for his political views, the human rights courts don't tend to like that sort of thing.

Is it not just a case of "murderous lunatic remains locked in asylum after criminal sentence until cured" - which can very well be until his death?