Police have arrested a man from the Leeds area in northern England in connection with last week’s bomb attacks in London in which at least 52 people died. On a day rich in developments, a spokesman said police were tracking the movements of four men suspected of carrying out the bombings. Assistant District Commissioner Peter Clarke, head of the anti-terrorist branch, told reporters: “We now know that all four of these men arrived in London by train on the morning of Thursday July 7th. We have identified closed circuit television footage showing the four men at Kings Cross station shortly before 8.30 am on that morning. One of the men who had set out from Yorkshire was reported missing by his family to the central casualty bureau shortly after 10 o’clock last Thursday. We have now been able to establish that he was joined on his journey to London by three men.”There is strong evidence that one of the four died in the blast at Aldgate, he said. The statement to the press followed dawn raids by police on six houses in the Leeds area that included the addresses of three of the four men. More than 500 people in the Burley area of Leeds were evacuated as police carried out a controlled explosion. Police also neutralised a suspect vehicle at Luton, north of London. The investigation is moving at great speed, Clarke said, but he warned that it was still in its early stages. Another spokesman said experts were examining tapes from more than 2,500 closed circuit television cameras posted around central London. Police are describing the operation as the biggest crime scene investigation in Britain’s history.