Oops! How the Blairs' new fixer, Martha Greene, appeared at No 10 ... and hastily retreated

Dressed in a white suit, she emerged momentarily from 10 Downing Street late on Wednesday.

But finding herself live on the BBC's Ten O'Clock News, in front of 4.6million viewers, she bolted bashfully back inside.

• Video: Click here to watch the moment Martha realised she'd been caught on camera

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So who was this shy woman in white, who, framed by the famous doorway, fleetingly appeared over the shoulder of BBC political correspondent James Landale as he delivered his report?

We can reveal that it was Martha Greene, the Blairs' "fixer" and confidante, and the woman supposed to be unobtrusively masterminding plans for Tony and Cherie's life after Downing Street.

Earlier that day the American businesswoman had been overseeing work on the Blairs' £3.6million townhouse in Connaught Square, where they will move after Mr Blair relinquishes power.

Miss Greene's late-night meeting and her movements within the space of 12 hours – back and forth from the two houses – provide the clearest evidence yet that she has become indispensable to the Blairs.

And they also suggest that they may be ready to move from No 10 sooner than has been predicted. After Wednesday's visit to Connaught Square, Miss Greene was back the next day to discuss the £100,000 facelift of the property with an architect and workmen.

Existing interior features, including an entire kitchen, have been dumped in a skip outside. A plumber working at the house said: "It's a major refurbishment."

Much of the project involves security precautions. The front door is being replaced by a steel-reinforced one and security men were seen checking locks on sash windows.

The planning application reveals details of a secluded sun terrace, four solar panels on the roof, a possible nanny flat and a self-contained basement area which could be used as a base for detectives.