Former Tory aide Carrie Symonds waits for a taxi outside her flat in London, where former Foreign Secretary Boris Johnson is reported to have moved in

Boris Johnson's girlfriend Carrie Symonds has been spotted leaving her £1million flat where the former Foreign Secretary is reported to have moved in.

The pair have been photographed laughing and smiling in the street outside the home and in one picture Ms Symonds appeared to pinch the ex-London mayor from behind.

Mr Johnson, 54, is said to 'adore' his 30-year-old partner and behave like a 'puppy dog' around her, and the pair are reportedly planning to 'come out' as a couple next month.

One source told the Sun: 'Obviously they've tried to be discreet about their relationship, so Boris has been spending time in Carrie's flat.

'Neighbours regularly see him shuffling out, woolly hat wedged down over his face, tottering off on his trusty push bike.

'The plan is to "come out" at an official Conservative party function towards the end of next month. Boris adores Carrie, and doesn't want to keep it a secret for much longer.'

The source said Ms Symonds even has a photograph of the 54-year-old MP as the screensaver on her phone.

The pair threw a pre-New Year's Eve party for close friends at which they reportedly could not keep their hands off each other, and seemed 'very much in love'.

It comes as sources close to the couple said that Boris, 54, has started divorce proceedings and is in a 'serious relationship' with Ms Symonds, after the pair found themselves at the centre of his highly-public divorce announcement last year.

The former Foreign Secretary's formal split from second wife Marina, also 54, began four months ago with a statement from the pair, although on Friday the Central Family Court said the Johnsons had yet to lodge formal divorce proceedings.

Mr Johnson, 54, has been dating former Tory spin doctor Carrie Symonds (pictured left), 30, since the summer. They are seen together right at the Boat Race in 2012

Mr Johnson is said to be so in love with Ms Symonds (pictured) that he behaves 'like a puppy dog around her'

It emerged last week that the couple enjoyed a romantic break over the New Year in a villa on Greece's Pelion peninsula. The pair are pictured together here at Conservative fundraising ball earlier this year

A friend of Mr Johnson told The Mail on Sunday: 'The divorce proceedings actually began in September. Boris and Carrie are in a serious relationship.'

The friend added that despite the huge interest in their love life from friends and political rivals, the couple were trying to stay tight-lipped over their relationship.

However, it emerged last week that the couple enjoyed a romantic break over the New Year in a villa on Greece's Pelion peninsula.

They were recognised by expat Chris Wicks as they dined out in a taverna in Lafkos.

Mr Johnson is said to be so in love that he behaves 'like a puppy dog around her'.

A friend said: 'He wants to get engaged. He's completely in thrall to Carrie. Totally loved-up.'

It emerged in September that Boris and his wife Marina were planning to divorce after 25 years of marriage. It came amid reports that father-of-four Mr Johnson had begun a relationship with Ms Symonds, a former Tory Party communications chief who is now an adviser to financial firm Bloomberg.

Another ally of Mr Johnson was quoted yesterday as saying Ms Symonds seems to makes him 'very happy'.

The friend added: 'Carrie has been the perfect girlfriend. He and Marina split in March, so it shouldn't be a surprise that this relationship is serious by now.'

The friend said the couple had been trying to 'keep things discreet', adding: 'Nobody wants to see Marina humiliated by public displays.'

It is understood Ms Symonds has yet to meet Mr Johnson's children.

In September when they announced they were to divorce, Mr Johnson and his wife stressed that 'as friends, we will continue to support our four children in the years ahead'.

The statement said the pair had decided several months previously that 'it was in our best interests to separate'.

They added: 'We have subsequently agreed to divorce and that process is under way.'

Mr Johnson and his wife had been living at the £20 million grace-and-favour home in Carlton Gardens, the official residence of the Foreign Secretary, until the end of July.

They own a £4 million townhouse in Islington as well as a country home in Oxfordshire.

Boris married first wife Allegra Mostyn-Owen in 1987. He married Marina, a QC, in 1993. The marriage survived a string of highly public affairs but the pair announced their intention to split, last year.

In 2004 the pair separated after it came out that Mr Johnson had had an affair with writer Petronella Wyatt - a relationship which cost him his job on the Tory front bench when Michael Howard discovered Mr Johnson had lied to him about it.

Six years later the marriage came under further strain when Johnson was reported to have had a child with art consultant Helen Macintyre.

While Mr Johnson was Mayor of London, it emerged that he was the father of a daughter conceived during an affair with Ms Macintyre. She lost a legal battle to keep her daughter's paternity a secret. During the hearings the appeal court was told that the girl, born in 2009, was allegedly the second child conceived by Johnson from affairs.

The case did not prevent Johnson from returning to the Commons in 2015 and then being made foreign secretary.

Carrie Symonds, daughter of Matthew Symonds, one of the founders of the Independent, and Josephine Mcaffee, one of the paper's lawyers, worked at Conservative head office for eight years.

She worked for current Home Secretary Sajid Javid, and for a time as an adviser to Zac Goldsmith, before being promoted to the role of Conservative communications chief.

She now works for Bloomberg in a role promoting clean oceans.