Lib Dem Care Minister Norman Lamb has been through the ordeal of his son being 'blackmailed ' A minister last night told how he became drawn into a 'nightmare ' blackmail plot over a video of his son taking cocaine . Norman Lamb , the Lib Dem Care Minister , had to call the police after his son Archie 's flatmate demanded cash from him and sent threatening messages . He paid the lodger £7,500 to move out but says the man then tried to ruin Archie 's career in the music business . Mr Lamb , 57 , said : 'This man has a violent past . We were worried for our safety . ' As his party unveiled the £1 billion boost to mental health services that Mr Lamb has campaigned for , the senior MP admitted his son has been through 'very dark periods ' . Archie , now 27 , was diagnosed with Obsessive Compulsive Disorder at the age of 15 and has been on medication ever since . He went into the music industry , founding a record label called Takeover Entertainment and becoming an early champion of rapper Tinchy Stryder , who went on to top the charts . But his father said that Archie had also fallen in with a bad crowd , leading to the blackmail attempt . 'He 's had amazing success and he 's also had some very dark periods , and that led to him drinking too much and , as we understand it , getting into bad company and drugs , ' said the North Norfolk MP . Mr Lamb added he was 'immensely proud ' that his son had escaped from his problems and rebuilt his career , and bought him a London flat where he could find 'peace and tranquillity ' . But then the alleged blackmailer , who is also thought to be 'the source ' of the drugs that Archie took , moved in . Mr Lamb took legal advice on how to evict his son 's flatmate and was told he should offer him £7,500 – money his son owed plus compensation for having to move out . Archie Lamb ( left ) with rapper Tinchy Strider . Mr Lamb said he is 'immensely proud ' his son had escaped from his problems and rebuilt his career before the recent alleged blackmail attempt . Despite handing over the cash , the tenant refused to leave – 'and at that point I concluded we were being blackmailed and we had to go to the police , ' Mr Lamb told the Sunday Mirror . He found out just last week that the man said he had a video appearing to show Archie snorting the Class A drug . 'This guy sought to blackmail my son , ' the Minister said . 'We were confronted with threatening emails , text messages saying things like 'underestimate me at your peril ' . We have been confronted by a criminal who has sought to blackmail us . ' The Sunday Mirror said the former flatmate insists he was simply trying to recover money he was owed . Police are reportedly looking into the case . The senior Lib Dem referred to the issue when he took to the stage at the party 's spring conference in Liverpool . He said : 'Before I begin my speech I just wanted to say a few words about . The senior Lib Dem referred to the issue when he took to the stage at the party 's spring conference in Liverpool . a personal matter , something you may have read about or heard about this morning . 'My family has had our own experience of mental health problems , as our oldest son was diagnosed with obsessive compulsive disorder at the age of 15 . 'It 's something he has made a decision himself to be open about . 'This has been a very painful time for our family . As a parent you just want to keep your children safe , to look out for them and to know that they are going to be OK. 'But my family is not unique . Our experience has made me even more determined to bring mental health out of the shadows and to fight for better care for all of the families affected . ' Mr Lamb , whose words were met with applause by the audience , added : 'Can I thank so many of you who have been so kind and supportive this morning . It is enormously appreciated , not just by me but by Mary my wife , and our whole family . '
Lib Dem Care Minister Norman Lamb had to call police after his son Archie 's flatmate demanded cash from him and sent threatening messages . Paid lodger £7,500 to move out but man then 'tried to ruin Archie 's career ' Alleged blackmailer claims to have video of Archie snorting Class A drug . Minister 's son founded record label and championed rapper Tinchy Stryder .