LONDON (REUTERS).- The Last Supper took place on a Wednesday -- a day earlier than thought -- and a date for Easter can now be fixed, according to a Cambridge University scientist aiming to solve one of the Bible's most enduring contradictions.

Christians have marked Jesus' final meal on Maundy Thursday for centuries but thanks to the rediscovery of an ancient Jewish calendar, Professor Colin Humphreys suggests another interpretation.

"I was intrigued by Biblical stories of the final week of Jesus in which no one can find any mention of Wednesday. It's called the missing day," Humphreys told Reuters. "But that seemed so unlikely: after all Jesus was a very busy man."

His findings help explain a puzzling inconsistency between the Gospels of Matthew, Mark and Luke, who said the Last Supper coincided with Passover and John, who said the meal took place before the Jewish holy day commemorating the Exodus from Egypt.

Humphreys' research suggests Jesus, and Matthew, Mark and Luke, were using the Pre-Exilic Calendar, which dated from the time of Moses and counted the first day of the new month from the end of the old lunar cycle, while John was referring to the official Jewish calendar of the day.

"It was an extremely curious mistake for anyone to make because for Jewish people Passover was such an important meal," said Humphreys, a metallurgist and materials scientist and a Christian.

"The contradictions have been known for a long time but not been talked about by the general public very much. I am using science and the Bible hand in hand to solve this question and showing the Gospels are actually agreeing, just using different calendars."

If the Passover meal and the Last Supper did take place on a Wednesday it would help explain how the large number of events that the Gospels record between the Last Supper and the Crucifixion were able to take place.

With the help of an astronomer, Humphreys reconstructed the Pre-Exilic calendar and placed Passover in the year AD 33, widely accepted as the year of Jesus' crucifixion, on Wednesday April 1.

That means if modern Christians wished to ascribe a date for Easter based on Humphreys' calculations, which he has been mulling over since 1983, Easter Day would fall on the first Sunday in April.

(Editing by Steve Addison)