Burglar walks into Downing Street waving girl's ID pass

Obadiah Marius strolled into the Cabinet Office building in Whitehall then wandered unchallenged around a number of unmanned offices used by Cabinet Office and Privy Council officials last June.

It is understood he walked near the Cobra emergency room where the Prime Minister coordinates the response to anti-terrorist emergencies and was close to the then Prime Minister Tony Blair's personal office.

Marius was only arrested and armed police called when he wandered out of No 9 Downing Street.

He was on bail at the time, having entered the judges' chambers at Snaresbrook crown court to steal three laptop computers worth £4,500.

Marius, 43, has 78 previous convictions for offences committed to feeding his drug habit and has spent most of his adult life in prison.

Six years ago he attempted to break into the TUC building in Crouch End Hill and specialises in burgling public buildings including theatres, schools and shops.

But despite his appalling record Judge Christopher Hardy today decided to give him "one last chance" and handed him a suspended sentence and a residential drug rehabilitation order.

Isobel Ascherson, prosecuting, told Southwark crown court that Marius and his girlfriend, 19-year-old Victoria-Smith, walked into the Cabinet Office at No70 Whitehall. The security guard on duty later told police that Marius "may have held up what I believed to be a building pass".

But the only security card the couple were later found to be carrying was Miss Smith's Lithuanian photo ID pass.

Miss Ascherson said: "The doors marked ministers were either unlocked for him or were not properly locked. He was followed through the door by his girlfriend carrying a plastic bag.

"In what was quite an astonishing breach of security this man and his girlfriend were let loose in the Cabinet Office at around 6pm. They went upstairs where there were a number of offices and nobody to be seen.

"They came back down, and they went straight into Downing Street through the Privy Council office at No 9 where the security guards challenged them.

"They said they were looking for work. Armed police became involved and a large security issue was raised about what they may have left behind them in the Cabinet offices."

The judge asked whether a full inquiry had taken place into the security breach. Miss Ascherson replied: "I would hope so but that is unrelated to these proceedings."

Marius was interviewed by police and insisted he thought he had just been in an ordinary office building where he could inquire about work.

But Ms Ascherson said: "It's very much the modus operandi of this man simply to enter buildings and see how far he can get."

Marius, of Battens Park, Stratford, pleaded guilty to two charges of burglary. Miss Smith was also charged but no evidence was offered against her and a formal not guilty verdict entered.

Marius's counsel Harry Potter described him as "a very longstanding prolific offender and it's no exaggeration to say he has spent the bulk of his adult life in prison".

He added: "These are embarrassing offences but they are not espionage but opportunist crime."

Sentencing, the judge said Marius was a "dishonest and persistent rogue". "Through an appalling lapse in security which one can only hope has been remedied you entered the very heart of government in Downing Street. You entered various offices but nothing was stolen there but quite clearly your purpose was to steal anything you could find.

"You deserve to go straight back to prison but you have been assessed as to whether you might be suitable for residential rehabilitation requirement. This is your last chance."

Marius has made 38 appearances in court since his first conviction for theft at the age of 13 and his first burglary at the age of 15. He will take part in a drug rehabilitation programme in Plymouth.

He was sentenced to 12 months imprisonment suspended for 18 months and placed under an 18-month supervision order.