Deadlock seal A deadlock seal was a form of lock or a device added to a lock that was almost impregnable . It was more secure than most locks . The Doctor ' s sonic screwdriver could not open regular deadlock seals , ( TV : " Bad Wolf " ) but these locks could be keyed to specific sonic devices , as Matron Cofelia did with her sonic pen . ( TV : " Partners in Crime " ) Deadlock encryption could be used to protect electronic files . ( COMIC : " The Sound of Our Voices " ) Features . Deadlocking made locks more difficult to open , at least with sonic devices . More sonic devices could be used in concert to break deadlock seals . ( TV : " Partners in Crime " ) Additional deadlocking could be applied , from double ( TV : " Voyage of the Damned " ) to triple . ( TV : " Partners in Crime " , GAME : " TARDIS " ) It was possible to create deadlock seals with a sonic device . The Doctor " locked " several things during his travels , particularly the controls of his TARDIS , which even the Master could not unlock . ( TV : " 42 " , " Utopia " , " The Sound of Drums " , " Last of the Time Lords " , " Invasion of the Bane " ) Deadlocking did not make glass unbreakable . ( TV : " The Poison Sky " ) It did , however , make metal incapable of being melted , or at least heated , and could prevent cords and doors from being separated or opened physically . ( TV : " The Time of Angels " ) Uses . The Big Brother House on the Game Station was fitted with deadlock seals after the contestants of an earlier edition of the show walked out . ( TV : " Bad Wolf " ) The Krillitane s used deadlock seals on several objects in Deffry Vale High School . ( TV : " School Reunion " ) The SS " Pentallian " ' s doors had deadlock seals that activate upon secure closure . ( TV : " 42 " ) The Heavenly Host s on board the " Titanic " were constructed with double deadlocked circuitry . ( TV : " Voyage of the Damned " ) Midshipman Alonso Frame used a " maximum deadlock " to seal the bridge of the Titanic . ( TV : " Voyage of the Damned " ) Adipose Industries Headquarters could be deadlocked , including the doors and windows . The deadlocks there could be activated remotely on command . The Inducer built into the building was said to be triple deadlocked . However , the Doctor was able to open these locks after acquiring the sonic pen of the owner of the building , Miss Foster . ( TV : " Partners in Crime " ) ATMOS devices developed by Luke Rattigan for the Sontaran s were deadlocked to their respective car s . They could deadlock the entire car . ( TV : " The Sontaran Stragem " / " The Poison Sky " ) John Hart ' s hypersteel handcuffs had a deadlock seal . He used them to lock himself to Gwen Cooper . ( TV : " Kiss Kiss , Bang Bang " ) Torchwood Three ' s Torchwood SUV was triple - deadlock sealed . ( TV : " " ) One particular Weeping Angel created deadlock seals on structures that weren ' t equipped with any such device . ( TV : " The Time of Angels " ) GSO Arctic Drilling Station had deadlocks in its security locks . ( GAME : " Blood of the Cybermen " ) The vase containing the Entity had a " triple - deadlock forcefield " . ( GAME : " TARDIS " ) A time ship had a deadlock seal on its activation console . ( TV : " The Lodger " ) The Flydon Maxima Research Base used a series of deadlock seals for protection . ( PROSE : " The Depths of Despair " ) The Pandorica used deadlocks as a security bypass . ( TV : " The Pandorica Opens " ) The lock for the cashier ' s office in a 21st century theatre had a deadlock seal . The Eleventh Doctor found this improbable , considering the technology level of Earth and such an unnecessary need for security . ( PROSE : " Snowfall " ) The headquarters for Lyttle Monsters Inc had deadlock seals for their doors . ( PROSE : " Snowfall " ) Cass , refusing to join the Eighth Doctor in his TARDIS because he was a Time Lord , closed and deadlocked a door on her gunship , preventing the Doctor from reaching her . ( TV : " The Night of the Doctor " ) River Song asked Flemming to deadlock the baggage hold of the " Harmony and Redemption " containing the Doctor ' s TARDIS and the body of her husband Hydroflax . According to her , only a genius could escape from it . ( TV : " The Husbands of River Song " ) The vault - like laboratory door at the SERVEYOUinc - operated United System Research Base was protected by a tenth - generation quantum - liquid - deadlock seal encryption . In addition , most sensitive files were deadlock - encrypted . ( COMIC : " The Sound of Our Voices " )