A Nixon in China moment

The shorthand is “Nixon goes to China,” meaning a moment in which a leader reverses his past positions to do something that is shocking but beneficial.

Richard Nixon is hardly a role model, overall; he was a devious president who encouraged illegal actions by his subordinates. But he was a clever strategist — never more so than in the opening to China that culminated in his February 1972 visit to Beijing...

...Nixon arguably was the only U.S. politician who could have gotten away with such a bold move. He had the right-wing credentials, as an anti-communist and advocate of Taiwan.

 David Ignatius, Washington Post 

In a similar way, Flip Chart Rick believes that Theresa May is counting on her right-wing credentials to sprinkle some of that fairy dust we call "credibility" onto previously derided Labour policies. He thinks we may be seeing:

...a shift away from free market ideology as Theresa May promises more interventionist policies, such as a cap on energy prices, a crackdown on companies who underfund pension schemes, investment in new council houses and the “greatest extension of rights and protections for employees by any Conservative government in history.”

Interesting, if true, although others doubt whether any such Damascene conversion has really happened ("Red Theresa my arse").

Whether or not you think the advertised policy shift is sincere, or even real, it's an interesting reminder that what's deemed politically possible often depends on who's doing or saying something, rather than the actual merits of what's being done or said. Which isn't, in my opinion, a good thing, although if the subsequent career of Richard Milhous Nixon did nothing to dent people's blind faith in the mystical power of "credibility", then I'm afraid nothing will.