THE CENTURIES-OLD Christian custom of marking Jesus and his disciples’ Last Supper on a Thursday could be a miscalculation of Biblical proportions, according to claims by a professor at the University of Cambridge.

The Mystery of the Last Supper, a book by Sir Colin Humphreys, claims to combine Biblical and astronomical research to resolve a longstanding conundrum created by apparently conflicting reports from various Gospels.

The Gospel according to John claims that the meal – supposedly the last dinner enjoyed by Jesus with his disciples before his crucifixion – took place before the beginning of the Jewish Passover feast, in conflict with the Gospels of Matthew, Mark and Luke.

Humphreys told the Daily Telegraph, however, that the calendar being used by the former was a different one to that used by Jesus and the three other evangelists – who used a popular old-fashioned Qumran calendar, instead of John’s official lunar one.

“If we use science and the Gospels hand in hand, we can actually prove that there was no contradiction,” Humphreys said.

The argument could also help to resolve another conflict among Biblical scholars, who have been divided for centuries over whether it was possible for Jesus to have been arrested and put to trial in the few hours between his Thursday night Supper and crucifixion on Good Friday.

The Sydney Morning Herald adds that the research is apparently thorough enough to put a date on the meal: it would have taken place on Wednesday 1 April, in the year 33 AD (the assumed year of Jesus’s death, assuming he was born at Year Zero).

Humphreys believes the latter conclusion could help to avoid the current practice where the dates of Easter are dictated by lunar cycles; currently Western Christanity sets the date of Easter to the first Sunday after the first full moon after March 21.

Instead, he argues, Easter could be fixed for April 5 – or, at the very least, the closest Sunday to it.

A similar theory to Humphreys’ was discussed by Pope Benedict XVI in 2007, when he acknowledged that Jesus probably held his last meal according to the Qumran calendar, which would have seen Passover meals held a day before the ‘official’ calendar.