Theology: Passover and Easter, When?

Saw this item today.

I knew that Jesus celebrated the Passover with his disciples prior to his death on Good Friday and Resurrection on Easter Sunday.

What I didn't know was that Matthew, Mark and Luke offered that description but that John stated that Jesus died on the day of preparation for the Passover (Friday) which results in a special Sabbath Saturday that was also a Passover remembrance.

Thus, it appears confusing and contradictory!

The article offers this explanation:
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.
.......
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.

If this analysis correct, Jesus celebrated Passover with his disciples as described in Matthew, Mark and Luke on a date (Wednesday) that was different then the establishment Jewish community of the time which celebrated it on Saturday which was what John was referring.

I look forward to seeing if some other scholars I check out on these theological matters agree with this proposed explanation.

UPDATE: Here you can hear Humphrey's explain in a BBC interview.