Was the Last Supper celebrated on Wednesday?

The story of the last week of Jesus’ earthly life (‘Holy Week’, or ‘Passion Week’) is told in great detail in the four Gospels.
But there are some apparent discrepancies which sceptics seize on in order to undermine the historical accuracy of the narrative.
For example, Judith Redman supposes that she is speaking for many when she states that ‘scholars who have looked at what we can know about the historical Jesus from the Gospels have generally decided that the answer is “not much”.’
Colin Humphreys opens his 2011 study by identifying the four main elements of the puzzle:
- What happened on the Wednesday of Holy Week? According to the usual chronology, the answer is, ‘Almost nothing’.
- What sort of meal was the Last Supper? According to the Synoptics, it was a Passover meal. But according to John, it was eaten on the day before the Passover.
- How can all the comings and goings involved in the trials of Jesus be fitted into the narrow time slot between finishing the Last Supper and the crucifixion (if the former took place on the Thursday evening, as is usually supposed)?
- How could the trials of Jesus have been legal, given the evidence that suggests that Jewish trials could not be held at night? (Although the Gospels say that there were false witnesses, they do not imply that the trials themselves were illegal).
Turning now the summary at the end of the book, Humphreys offers the following reconstruction:
- The Last Supper took place on the Wednesday evening, the 1st April AD 33.
- As stated by the Synoptics, it was a Passover meal (according to the pre-exilic calendar).
- John refers, however, to the official calendar, according to which the Passover was held on the Friday, with the first Passover lambs being slain at the time of Jesus’ death (about 3pm on 3rd April AD 33). This official calendar had been adopted by the Judean Jews when they were in exile in Babylon in the 6th Century BC.
- The pre-exilic calendar continued in use through to the 1st century AD by groups such as the Samaritans, Zealots, and some Essenes. It would not have been particularly odd for Jesus to choose to use this calendar to celebrate his Last Supper as a Passover meal. Indeed it would have been natural for him to do so, given that he saw himself as the new Moses, and therefore had good reason to hold his last Passover meal on the anniversary of the very first Passover meal as described in the book of Exodus.
- A Wednesday Last Supper solves the puzzles outlined above. It accounts for the ‘lost day’ in the middle of the Passion week. It resolves the apparent discrepancy between the accounts of the Synoptics and John. It allows sufficient time for all the events that happened between the Last Supper and the crucifixion. It means that the trials of Jesus were legal: the main trial being held during the day on Thursday, with a further meeting the following day to confirm the verdict.
Of course, I’m omitting the details argumentation which takes up the bulk of the book. But I’ll leave it at that for the moment, as a more than plausible working hypothesis when trying to piece together the Passion narrative.
Humphreys, Colin J. The Mystery of the Last Supper (pp. 192-195). Cambridge University Press. Kindle Edition.