Since being appointed head of Scotland Yard's Anti-Terrorist Branch last month, one of his main objectives has been to keep a low profile. Commander Tucker does not give interviews because 'he does not want to be turned into a media celebrity', Scotland Yard insisted.
Described by colleagues as a 'quiet, modest, and hard-working man', it caused some surprise within the Metropolitan Police when he replaced the hard-nosed, high-profile George Churchill- Coleman.
Mr Tucker, an intelligence specialist, intends to be different. Aged 50, married, and living in south-west London, he wants to remain as anonymous as possible. He wants his team to reflect his personal style of quiet efficiency, according to a senior Met officer. 'He has gone through the ranks and become a strategic thinker. He thinks details through. He sees himself as more of part of a jigsaw.
'He will bring a different dimension to how the attacks are dealt with. He wants to avoid platitudes and take some of the personality out of the job. He's a product of the newer style of management and leadership in the service. Ten years ago he might not have made this post.'
Born at Exeter in 1942, Mr Tucker did a number of jobs including working as a sales assistant in the Post Exchange - the PX - at the United States embassy in Paris.
In 1964, aged 22, he joined the Metropolitan Police. He spent three years on the beat in East London and worked his way up the ranks in the CID with stints on the Fraud Squad and the Criminal Intelligence Branch. As a superintendent he became head of the Yard's Interpol unit.
Probably his highest profile assignment was as the detective superintendent in charge of the case of Everald Irons, the man dubbed the Putney Rapist. Irons was jailed for 18 years in July 1988 after being convicted of six rapes. This was a particularly sensitive investigation because Irons' wife, Anne, was an officer in the Metropolitan Police.
Two years ago Mr Tucker became head of SO11 - the Criminal Intelligence Branch - a unit responsible for the collection of criminal intelligence and its evaluation and surveillance operations.
His interests and skills are listed as a trained hostage negotiator, golf, swimming, fluent French and 'some Spanish'. He also enjoys reading.
His understated style means he is not particularly well known within the police. An officer who does know him well said: 'He's a serious type of person and has a small band of friends outside the police. He'll go for one, maybe two drinks, with his colleagues rather than a session.
'If you saw him in a group you would not think he is a leader - not someone who stands out in a crowd. He's very modest.'
But on Thursday he was on television to condemn the IRA attack in which two bombs exploded injuring four people in central London. 'This seems to be a continuance of this obscene game which the IRA wishes to play with the police,' he said. Mr Tucker is out from the shadows.