Christians have long celebrated Jesus Christ's Last Supper on Maundy Thursday but new research released Monday claims to show it took place on the Wednesday before the crucifixion. Professor Colin Humphreys, a scientist at the University of Cambridge, believes it is all due to a calendar mix-up -- and asserts his findings strengthen the case for finally introducing a fixed date for Easter. Humphreys uses a combination of biblical, historical and astronomical research to try to pinpoint the precise nature and timing of Jesus's final meal with his disciples before his death. Researchers have long been puzzled by an apparent inconsistency in the Bible. While Matthew, Mark and Luke all say the Last Supper coincided with the start of the Jewish festival of Passover, John claims it took place before Passover. Humphreys has concluded in a new book, "The Mystery Of The Last Supper", that Jesus -- along with Matthew, Mark and Luke -- may have been using a different calendar to John. "Whatever you think about the Bible, the fact is that Jewish people would never mistake the Passover meal for another meal, so for the Gospels to contradict themselves in this regard is really hard to understand," Humphreys said. "Many biblical scholars say that, for this reason, you can't trust the Gospels at all. But if we use science and the Gospels hand in hand, we can actually prove that there was no contradiction." In Humphreys' theory, Jesus went by an old-fashioned Jewish calendar rather than the official lunar calendar which was in widespread use at the time of his death and is still in use today. This would put the Passover meal - - and the Last Supper -- on the Wednesday, explaining how such a large number of events took place between the meal and the crucifixion. It would follow that Jesus' arrest, interrogation and separate trials did not all take place in the space of one night but in fact occurred over a longer period. Humphreys believes a date could therefore be ascribed to Easter in our modern solar calendar, and working on the basis that the crucifixion took place on April 3 , Easter Day would be on April 5.