Police officers conducted a series of raids in London on Friday
Friday was hailed as the Metropolitan Police's "best day" since the 21 July bombing attempts on London, after raids in the capital and Rome resulted in a number of arrests.
Police believe they now hold all four suspects for the failed Tube and bus attacks.
Metropolitan Police Commissioner Sir Ian Blair had said the attacks and subsequent investigation would "reshape British policing".
Despite the fast-pace of raids and arrests, he said the force would need to look at what effect terrorism would have on policing.
"Can we do all of this mission if this is going this way? And if we
can, then what's the sort of additional cost that is required?" he told the BBC's Newsnight.
Two weeks after the 7 July attacks, another four men targeted Tube trains at Oval, Warren Street and Shepherd's Bush stations, and a number 26 bus in east London.
The manhunt that followed the attempts was described by Sir Ian as "the largest investigation the Met has ever mounted", with officers hunting suspects both in the UK and abroad.
Some 15,000 CCTV tapes have been studied by officers, along with 1,800 witness statements. More than 5,000 calls have been made to the anti-terror hotline.
The first significant police action following the attempted bombings resulted in the death of an innocent man.
Brazilian national Jean Charles de Menezes, who was working in London as an electrician, was shot dead by police at Stockwell station, south London, on the morning of Friday 22 July.
However, police continued to act on leads and later that day an arrest was made in Stockwell and officers raided a flat in Streatham Hill, also in south London.
Sir Ian Blair called for more 'good old fashioned detective work'
A subsequent series of raids were carried out across the capital, resulting in the discovery of possible explosives in a car at East Finchley.
A package found in bushes at Little Wormwood Scrubs in north-west London was also believed to be linked to the attacks, with speculation that a fifth bomber may have abandoned his plans at the last minute.
The release of CCTV images of the four suspects, along with the names of two of the would-be bombers, prompted more than 500 calls and e-mails to police, aiding the inquiry.
Another break came on Wednesday when police arrested four men at two addresses in Birmingham.
One of the men was named as Yasin Hassan Omar, wanted as a suspect in the Warren Street attempted bombing.
On the same day, three women were also arrested at Blair House, 200 yards from Stockwell Tube station, in south London, on suspicion of harbouring offenders.
A further nine men were arrested in raids on two addresses in Tooting, south London.
On Friday police carried out a series of raids in the north Kensington and Notting Hill areas of London, resulting in the arrest of three men, two of whom are suspected of being 21 July bombers.
They are Muktar Said Ibrahim - suspected of trying to bomb a bus in Shoreditch - and Ramzi Mohammed, wanted over the attempted Oval Tube bombing.
Police are investigating whether the third man, who has not yet been named, could have been a possible fifth bomber.
Despite the quick pace of developments, Sir Ian said British policing is facing difficulties in tackling terror attacks.
"I think there has to be a substantial increase in three fields," he told the BBC.
"It's detective work (that) we actually need, this
is good old-fashioned detective leg work.
"We need firearms capability. We've got enough firearms officers but not enough to do this length of tour.
"People have to have a rest. They can't just
keep carrying a gun hour after hour, day after day.
"Thirdly it's around the forensics and counter-explosive activity.
"We're pushing at the specialist areas and that is a difficulty for us".
Investigators will now be looking at who was behind the attacks and who recruited the July 7 and 21 bombers.
BBC security correspondent Frank Gardner said there were also fears that an unknown terror cell could still be at large in Britain.