Christians have long celebrated The Last Supper of Jesus Christ on Maundy, the Thursday before Easter, but new research released Monday claims that evidence shows it took place on the Wednesday before the Crucifixion.

Prof. Colin Humphreys, a scientist at the University of Cambridge in England, believes the mistaken date is due to a calendar mix-up -- and says his findings strengthen the case for finally introducing a fixed date for Easter, AFP reports.

In his attempt to pinpoint the exact timing of Jesus’ final meal, Humphreys used a combination of biblical, historical and astronomical research

The Bible’s different versions of Jesus’ Last Supper with his disciples have left researchers puzzled for centuries.

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, AFP reports.

In his new book, "The Mystery Of The Last Supper," Humphrey’s concludes that Jesus, along with Matthew, Mark and Luke, may have been using a different calendar than John was.

"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.

Humphreys' theory is that Jesus went by an old-fashioned Jewish calendar rather than the official lunar calendar that was in widespread use at the time of his death and is still in use today, AFP reports.

This would put the Passover meal -- and the Last Supper -- on the Wednesday, explaining how so many 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 occurred over a longer period.

According to Humphreys, the set date for Easter Day should be April 5.