"How on earth could the Lib Dems arbitrarily cancel Brexit??"

You don't know what your own party's policy was 59, that's bizarre. Here's your answer, this is from the Guardian 16th September,

" Lib Dems no longer want a second Brexit referendum; instead they would simply revoke article 50 without a public vote."

As your lefty bible the Guardian says, it was official LibDem policy to revoke A50 without a 2nd referendum, the EU had already said that would be perfectly acceptable to them, so Bob's your uncle and we're back in. 17.4 million votes nullified at a stroke, I'm not sure even Stalin, Mussolini or Hitler ever tried to pull such a stunt and they were a trio of rum buggers to put it mildly. The EU aren't overkeen on democracy either, but at least when they lose a referendum, they go away, do a bit of bullying, a bit of cajoling, alter some of the wording and then have another referendum, and keep on having them until they win. But not the LibDems, result arbitrarily invalidated, 17.4 million votes flushed down the toilet, fascistic or what ?

"Hanging was an issue that divided the country. It was finally abolished in 1969 after many years of argy bargy from both sides.
There is a move by some Tory MP's to bring hanging back"

But it's not the policy of any mainstream party 59, I would like an example of a more extreme policy than the LibDem policy of arbitrarily overturning the biggest democratic vote this country has ever had. You're struggling aren't you.