<P> This stage takes place after the auditions have been completed, and is also referred to as Deliberation Day, in which the judges look through the acts that have successfully made it to this stage, and begin whittling them down to those who would stand a fair chance in the live semi-finals . The amount that goes through has varied over the show's history, though usually consists of a number that can be divided equally over the semi-finals being held in a series . Once the judges have decided on who will go through, all contestants that have reached this stage are called back to discover if they will progress into the live semi-finals or not . After this has been done, the acts are divided up between the semi-finals that the series will have; usually eight in each series, except for the sixth to tenth series which had nine acts per semi-final . </P> <P> For the fifth series, some acts were asked to perform again, as the judges had had difficulty coming to a final decision on the semi-finalist, and thus needed to see their performance again in order to make up their minds; it is only time in the show's history that this has happened, and has not been repeated since . </P> <P> Contestants that make it into the semi-finals by making it through the auditions and being chosen by the judges (or, from series 8, received the Golden Buzzer during their audition), perform once more before an audience and the judges, with their performance broadcast on live television . Until the tenth series, live episodes were broadcast from The Fountain Studios in Wembley, the same site used for The X Factor, but following its closure in 2016, the show relocated its live episodes to Elstree Studios in 2017, before moving to Hammersmith Apollo the following year . Like the Audition stage of the contest, each semi-finalist must attempt to impress by primarily conducting a new routine of their act within the same span of time; the judges can still use a buzzer if they are displeased with a performance and can end it early if all the buzzers are used, along with giving a personal opinion about an act when the performance is over . Of the semi-finalists that take part, only two can progress into the final, which is determined by two different types of votes - a public phone vote, and a judges' vote . </P> <P> The phone vote, which occurs after all the semi-finalists have performed, determines the first winner of the semi-final and takes place via a special phone line over a short break from the programme . During this time, the public votes for the act they liked best, through a phone number in which the final two digits are different for each semi-finalist - these digits are primarily arranged by the order of their appearance . Once the lines have closed and the votes have been counted, the programme airs a live results episode, in which the semi-finalist with the highest number of votes automatically moves into the final . The second winner is determined by the judges' vote, which held after the results of the phone vote have been given out, and determines whether the second or third most popular semi-finalist in the public vote moves on to the final . The judges' vote, held after the result of the phone vote, determines the second act that wins this stage, and is conducted between the second and third most popular acts the public voted on . After the number of judges was increased to four, the rule on the judges' vote was modified - if the vote is tied, the semi-finalist with the second highest tally of public votes automatically moves on to the final . For the eleventh series only, the judges' vote was not used, meaning that the finalists were determined by the public vote only - the semi-finalists in each semi-final for this series with the highest and second - highest tally of votes, moved on to the final . From the start of the sixth series, the show introduced a new format known as the "Judges' Wildcard", in which the judges can reinstate an act that had been eliminated from the semi-final, through a private vote conducted before the airing of the final . This format was later expanded to include a "Public Wildcard", in which the public could vote on an act that had been eliminated in the semi-finals during the judges' vote and reinstate it for the final; although used in the ninth and tenth series, this format was dropped for the eleventh series . </P>

Where is britain's got talent semi finals filmed