The 456 The 456 ( pronounced " four - five - six " ) was an alien race that negotiated secretly with the British government in 1965 , and again in 2009 . This designation was given to them by human s based on the radio wavelength they used , and they took on the name as their own in their dealings with humans rather than offering the actual name of their species , if any ever existed . As they later revealed , they were drug dealers . The 456 used children as " the hit " because the bodily chemicals they create " felt good " . Biology . Humanity knew very little about the 456 ' s biology and anatomy , as they only had contact with one member of the species , who remained within a nearly opaque gas , contained within a transparent chamber . The natural design of their body consisted of three " head s " , connected to one body via three long necks . ( TV : " " ) The 456 thrived in an atmosphere made up of 25 % nitrosyl chloride , 22 % hydrogen chloride , 20 % nitrogen , 12 % fluorine , 9 % hydrogen cyanide , 6 % acetone , and 6 % phosgene . ( TV : " " ) It was later revealed by the creature itself that the individual may have been under the influence of a recreational drug the entire time , the effects of which were not fully known . The 456 ambassador emitted a viscous green fluid in moments of frustration ; this may have been an effect of either the use of recreational drugs or a natural response . ( TV : " " ) Their blood was red ( though this may have been from the human child connected to the individual ) . ( TV : " " ) Technology . The 456 had technological systems which could match the systems of the human race from 1965 onwards , such as radio telecommunications . They spoke English fluently and understood it perfectly ; this may or may not have been through the use of a translator . They seemed to be far more advanced than the human race , indeed far more advanced than most other species , having the chemical and biological knowledge to provide a range of virus es and anti - viruses to humans . ( TV : " " ) The 456 arrived on Earth in what was described as a pillar of fire , allowing them to teleport into a specially made tank , despite it being within a building . When the pillar of fire appeared , clouds would gather around it and then dissipate once the pillar was gone . This pillar of fire appeared to do no damage to Thames House despite passing through at least the roof . UNIT believed that their base of operations was somewhere in orbit around Earth , but they were unable to find their ship , suggesting that the 456 possessed advanced cloaking technology . ( TV : " " ) After the apparent death of the 456 ambassador , the 456 teleported his remains out in a similar way , with the remains disappearing into the sky in the form of a pillar of fire streaking upwards from Thames House instead of down into it . ( TV : " " ) In 1965 , the 456 took the children using a different method involving them walking into a bright light that disappeared in a flash rather than a pillar of fire . ( TV : " " ) They could also manipulate the minds of millions of children at will . When they came to Earth in 2009 , they forced all children globally on Earth to chant " We are coming " . The transmissions became more and more sophisticated with each sending , until the 456 manipulated each country ' s children into relaying a different message to their governments . Children around the globe communicated in English only , due to the 456 ' s previous dealings with the British government . This connection they could also give off a fatal signal , which they used to kill Clement McDonald . ( TV : " " , " " ) However , if reversed in a constructive wave , the frequency was deadly to the 456 , making their bodies exhibit extreme pain before violently exploding . As well , the 456 using the children in this way made them vulnerable to someone using the children as a transmitter in reverse to broadcast the deadly signal to the 456 . ( TV : " " ) Culture . The 456 used human children as a source of drugs . They would forcibly attach a child to their body with a life support system . This allowed the child ' s chemicals to stimulate feelings of pleasure in the 456 . During the process — according to the ambassador — the child felt no pain and lived long beyond its natural lifespan . However , it was conscious throughout the experience and had to use a respirator to survive in the toxic atmosphere . The entire reason for their visits to Earth were to get more children for the drug the children supplied them . ( TV : " " , " " , " " ) The real name of the species , if any existed . is unknown . In 1965 , they didn ' t give the human race a name when making a deal . In 2009 , after confirming that humanity ' s name for them was 456 , they chose to go by that name , suggesting that they purposefully avoided giving away any sort of detail about themselves . ( TV : " " , " " ) This is further suggested by the 456 instantly removing any remains of the 456 ambassador following his apparent death , denying the human race the chance to study the remains or even confirm the ambassador ' s death . ( TV : " " ) Though the 456 possessed the ability to communicate through radio waves , they chose to take over the children of Earth to send their messages . Dekker suggested to John Frobisher that this was simply " because they could " and to act as a scare tactic for the human race in advance of their arrival . ( TV : " " ) This tied in with the 456 ' s tactics of using threats and intimidation to get what they wanted . When approaching the human race for children in both 1965 and 2009 , the 456 asked for them as a " gift " in exchange for their help . In 1965 , the 456 offered something of equal value in return , but did not do so in 2009 . Instead , the 456 issued threats if they did not get what they wanted . Gwen Cooper suggested that the visit in 1965 was the 456 essentially setting up a " protection racket " to prepare for their eventual return and greater demands . ( TV : " " , " " ) The 456 chose to act through a great deal of shock and awe tactics . Along with using the children of Earth to send their various messages , they used a giant pillar of fire that was visible for miles around for teleportation . ( TV : " " , " " ) When Captain Jack Harkness threatened war between the human race and the 456 , the 456 ambassador released a deadly virus into the atmosphere of Thames House to kill dozens of people and demonstrate how deadly a war between humanity and the 456 could be . ( TV : " " ) However , despite their high level of technology and deadly demonstration , the 456 chose not to pursue a war with or the extermination of the human race as threatened when they were defeated . After an attack that apparently killed the 456 ambassador , the 456 removed his remains from Thames House and retreated without any form of retaliation for either the apparent death of the ambassador or the human race ' s ultimate defiance to their demands . Ultimately , the 456 preferred intimidation and threats to all - out war and when faced with such , chose retreat rather than battle . ( TV : " " ) In this way , the 456 were similar to the Monks who possessed advanced technology but retreated without a fight when the human race , aided by the Twelfth Doctor , defeated their invasion years after the 456 incident . ( TV : " The Lie of the Land " ) History . First contact . The 456 first made contact by radio on the wavelength sometime during or prior to 1965 . The 456 had learned English and knew something of Earth culture . In 1965 , Andrew Staines , Ellen Hunt , Michael Sanders , and Jack Harkness executed a deal with the unseen aliens . In exchange for twelve human children , the 456 gave them an anti - virus for a mutated strain of Indonesian influenza , which would otherwise , according to the aliens , have killed millions . These projections were agreed to by British analysts . The 456 claimed that the children would not be harmed , and in fact " would live forever " and that the 456 would not return to Earth . ( TV : " " , TV : " " ) Twelve orphan s were taken from the Holly Tree Lodge orphanage under the pretence that they were to go to another orphanage called Harbour Heights . These children were brought to a location in Scotland , where they were ushered into a white light . For unknown reasons , the 456 decided to leave behind one orphan , Clem McDonald , who ran off alone into the night . Torchwood Three later speculated that they weren ' t interested in him because he was on the brink of puberty . ( TV : " " ) Second contact . Initial contact . In September 2009 , the 456 sent a message through every child — ages five to eleven — on the planet : " We are coming . " ( TV : " " " " ) They followed with detailed instructions sent secretly to Dekker for a purpose built , gas filled chamber to be constructed for them on Floor 13 , the top level of Thames House , MI5 ' s headquarters in London and the most secure building in Britain . Technicians set about constructing the containment facility before the aliens ' arrival . ( TV : " " ) Arrival . On their arrival day , an ambassador transported itself from the sky in a pillar of fire into the chamber , and began negotiations with John Frobisher , whom Prime Minister Brian Green had had appointed informal ambassador . They insisted on addressing all the major powers , but Frobisher was able to convince them to keep quiet about the earlier dealings with the British government in 1965 . The 456 asked for a " gift " of 10 % of the world ' s children , in exchange for not destroying the human race . ( TV : " " ) The request was denied and the UK government offered sixty - seven hundred children of Failed Asylum Seekers ; the 456 rejected this offer and used the children of each country to tell the respective governments the number of children required by the 456 . The arrival of Jack Harkness led to an argument with the 456 , who released a virus into the air of Thames House as a demonstration of what the people of Earth would get if they didn ' t comply . This killed almost everyone in Thames House , including Ianto Jones and temporarily Jack Harkness . With no other choice , the governments of the world reluctantly agreed to the 456 ' s demands , now seeing fighting back as useless . ( TV : " " ) Resolution of the crisis . Now represented by Colonel Augustus Oduya of UNIT , the governments of Earth conceded to the demands of the 456 and began collecting the children . In particular , the government of the UK began using the children from the lowest performing schools in the country . At Colonel Oduya ' s request , the 456 ambassador revealed that they were drug traders , seeking the children of Earth for the " hit " the children ' s chemicals gave them . As the children were collected , Alice Carter convinced Johnson to work with Jack Harkness to defeat the 456 and to save the children of Earth . Jack realised that the signal the 456 used to kill Clement McDonald was new and if he turned it into a constructive wave , it could be used to defeat the 456 . Jack used the children of Earth as one giant transmitter to send the signal to the 456 with his own grandson acting as the prime transmitter . The transmission caused the 456 ambassador to writhe in pain before appearing to violently explode . Immediately afterwards , the ambassador ' s remains were removed from Thames House in another pillar of fire . With the apparent death of their ambassador , any surviving 456 retreated from Earth rather than retaliate . ( TV : " " ) The 456 would become the namesakes of various resolutions and changes to laws across the globe , including the 456 Regulation in Great Britain and the 456 amendments to U . S . Code 3184 . The 456 Regulation declared the members of Torchwood Three officially deceased , and the 456 amendments allowed the extradition of the Torchwood team into the United States when captured . ( TV : " The New World " )