Brown, accompanied by London Mayor Ken Livingstone and his Parisian counterpart Bertrand Delanoe, laid flowers at a memorial garden at King's Cross railway station in memory of 52 commuters who died in the July 7, 2005 attacks.

The low-key ceremony -- Brown did not speak, simply bowing his head for a few minutes in quiet contemplation -- contrasted with last year's programme of commemorations and came with the capital still jittery over security.

Last Friday, two car bombs, including one outside a packed city centre nightclub, failed to go off in London, while the day after, a flaming Jeep Cherokee slammed into Glasgow airport in Scotland.

The first man to be charged over the botched attacks, 27-year-old Bilal Abdulla, was to appear at City of Westminster Magistrates' Court in central London Saturday for a preliminary hearing.

He was charged with conspiring to cause explosions by police Friday night but his full trial will not take place for months.

The charge covers a period from January 1 to July 1, alleging he "unlawfully and maliciously conspired with others to cause explosions of a nature likely to endanger life or cause serious injury to property in the United Kingdom".

It carries a maximum sentence of life.

Abdulla was one of seven people detained in Britain over the attempted attacks. The others remain in custody, while one is under armed guard fighting for his life in hospital after suffering 90 percent burns.

Hundreds of thousands of visitors are likely to flock to London Saturday for one of the busiest weekends in the capital's calendar.