Mitt Romney isn't just meeting political leaders on his visit to London - he's doing some serious fundraising too. But his trip didn't get off to the best of starts.

Romney at No 10 (reuters)

It probably wasn't the most diplomatic way to begin his London trip - but Mitt Romney told US television network NBC that he wasn't sure if Britain was really ready to host the Olympic Games. A few things were "disconcerting", he said, like the problems with security firm G4S.

And he questioned the commitment of the British public. "Do they really come together and celebrate the Olympic moment? That's something which we only find out once the Games actually begin."

Later the Republican presidential hopeful posed with the former prime minister Tony Blair, and held the briefest of meetings with Ed Miliband, somewhat eccentrically addressing him as "Mr Leader". By the time he got to Number 10, for talks with David Cameron, he was back on-message, saying he was inspired by the enthusiasm shown by people lining the route of the Olympic torch relay.

Do they really come together and celebrate the Olympic moment? That's something we only find out once the Games acutally begin. Mitt Romney

But even before Mr Romney touched down in the UK, his team was already trying to row back from controversy - distancing themselves from remarks by an adviser who told the Telegraph his boss would restore the shared "Anglo Saxon heritage" to the Anglo-American relationship. The Democrats were quick to hit back at that one, with Vice-president Biden accusing him of "playing politics with international diplomacy."

But beyond the political meetings, a big feature of Romney's London trip is fundraising: with an exclusive bash at an undisclosed Mayfair location this evening, where tickets cost up to $75,000 a head.

Until now, Barack Obama has been way out in front in the overseas fundraising stakes - pulling in more than $2m from wealthy expats, compared to just over $1m for Romney. But all that is about to change.

Bankers' bash

Tonight's bash was to be hosted by the former Barclays chief executive Bob Diamond - but due to a few local difficulties over the Libor scandal, he "decided to step aside", according to a statement from the bank. Luckily one of Barclays' chief lobbyists, Patrick Durkin, was on hand to take over at the event: a man who has already raised more than a million dollars for Romney 2012, according to OpenSecrets.

A glance through a list of the other co-chairs reveals a plethora of bankers and City financiers. There are exectives from Credit Suisse, HSBC, Goldman Sachs, and Bain Capital Europe. One of them, fellow Mormon Eric Varvel, has given $100,000 to Restore Our Future, the political action group supporting Romney's campaign.

One Democratic politician, state representative Diane Russell from Maine, has launched an online petition demanding a full list of those who turn up to the party: "We believe politicians should work for us, not their corporate sponsors. It is time for Mitt Romney to fully disclose his donors - and how much they are giving to his campaign."

But although there is no public guest list, the Center for Responsive Politics says Barclays is the biggest source of Romney's overseas campaign donations. Eleven British MPs signed an early day motion urging Barclays to stop raising funds for Romney, although the bank inisisted they were non-partisan.

A statement from Cyrus Ardalan, head of UK and European government relations, said: "All political activity undertaken by Barclays' US employees, including personal fundraising for specific candidates, is done so in a personal capacity, and not on behalf of Barclays."

Game on

But back to the main event: the Olympics - and a chance, hope Team Romney, to remind voters back home that their man famously rescued the Salt Lake City winter games from disaster. Or, if the Democrats have their way, a chance to remind voters back home that Romney is a tax-avoiding, job outsourcing billionaire with a horse in the Olympic dressage event.

While Mitt will be enjoying plenty of photo-ops at Friday's opening ceremony, his rivals have put out an ad mocking Romney's business record and his reported investment accounts overseas. And then, there's the horse. Rafalca has already been the subject of a Democratic video making fun of "Mitt Romney's favourite sport - horse danging - and his favourite pastime - dancing around the issues."

Now there's a fake Twitter account, @RafalcaRomney - which declares "I dance for Mitt, so you don't have to." Amid all this, the New York Times reports that the US Olympic committee isn't just keeping journalists well away from the horse and its trainers - the news media have been banned from the merest glimpse.

As for Romney, he has been at pains to insist that he's going nowhere near the animal either, claiming he wasn't going to watch the dressage event, and didn't even know when it was scheduled.

From questioning the enthusiasm of his British hosts, to a prancing horse he is surrounding in secrecy: so far, Romney's Olympic trip isn't exactly covered in gold. A charm offensive, that has proved rather more offensive, than charming.

Felicity Spector writes about US affairs for Channel 4 News