Foreign adventures cannot obscure May's Brexit backdrop

It's nearly wheels-up time on the prime minister's latest big overseas adventure.

Touching down in China will provide Theresa May a temporary geographic escape from her critics. But this trip is also a desperately needed chance to project authority.

Like it or not, in politics the images that voters see matter, and matter a lot. So leaders often invest a lot in the art of looking important.

Whether taking part in a particular local ritual, inspecting the troops, gripping and grinning as another diplomatic handshake is documented for posterity.

No 10's hopes for the next few days range beyond peace and quiet without mobile phone signal on the plane. Aides to Theresa May might well enjoy that part too.

Major effort goes into planning these voyages, the topics chosen for discussion, provocative enough to be interesting, not so controversial as to be diplomatically awkward. The photo opportunities are planned meticulously.

In a moment more ridiculous than anything The Thick of It's script writers could have come up with, one former senior politician's team, whose blushes I shall spare, spent considerable powers of persuasion on a foreign visit - in other words, frantic phone calls - cajoling the driver of a golden boat to stay in position on a lake to make the backdrop of the images of their boss look good.

Neither the tide, nor the language barrier, made that easy.

But foreign trips are also notorious for providing opportunities for things to go wrong. Theresa May's early dash to the Trump's White House seemed such a good idea to Number 10 at the time, before the image of him grasping her hand, then his announcement of the travel ban while she was in the air.

By the time the No 10 team and we, the travelling press pack, landed in Ankara, shock had gone round the world and the UK had to give an answer.

Theresa May's reluctance to do so may have hampered the last stage of what her team had hoped would be a triumphant trip, ending with journalists heckling her when she refused to give a full answer.

Not surprisingly, by the time we landed back at Heathrow, the government had concluded it needed to clarify and a new line was emerging just as the bedraggled and exhausted lobby poured off the plane.

This time, the trip begins with the Tory Party already in a distinctly grumpy mood. To send Theresa May on her way, a joint article has found its way to The Sun, by three well known MPs, Nick Boles, Robert Halfon and Nicholas Soames, demanding that Number 10 ups its game and turns the screw.

Their frustration is that Downing Street's plans for the country aside from Brexit aren't bold enough.

It's more diplomatic than Mr Boles' recent description of some members of the government as "boiled rabbits", but it hardly dampens down the perception that Theresa May is somehow falling short.

And on the other side of the Tory debate, where Brexiteers have been even more rattled of late, one of their own side, Liam Fox, warning in The Sun they may have to "live with disappointment". (Although Mr Fox has since told the BBC he was referring to people who were plotting against Mrs May)

Eurosceptic efforts to increase the pressure in the last week or so have been directed at the Cabinet as well as the prime minister, in the hope of forcing Brexiteer ministers to be more forceful in the crucial debates. Mr Fox's intervention therefore could have the opposite of its desired effect.

In the next few days, Theresa May will have put physical distance between herself and her woes, but she can't hide from her party's problems.

Any number of smiling, carefully choreographed photo opportunities abroad can't change the domestic backdrop. However successful any prime minister's trip might be, they eventually have to fly home.