As superstitions go, being wary of the ides of March is certainly more unusual. Yet the day does have a certain resonance.

In the complicated world of the Roman calender, there were 45 public festivals (not bad compared to the UK's eight bank holidays), as well as the ides of each month, days which were sacred to Jupiter.

In March, May, July and October, the ides fell on the 15th.

The Julian calendar, established by Julius Caesar, gave us the basis of our system of 365 days a year and 366 in a leap year. But for the most part, the Roman festivals of his time have had their day.

The ides of March, however, is one day that continues to appeal, marked because that was the date that Julius Caesar was assassinated in the senate, in 44BC.

Its modern-day memory is thanks, like so many things, to Shakespeare's way with words.

In act one, scene two of Julius Caesar, Caesar asks a soothsayer what the future holds.

Caesar: Who is it in the press that calls on me?
I hear a tongue, shriller than all the music
Cry "Caesar!" Speak. Caesar is turn'd to hear.
Soothsayer: Beware the ides of March.

Although today the reference will not be understood by everybody, David Ewing Duncan, author of The Calendar, wrote that it was not always so.

A Roman saying "four ides" (meaning four days before the ides) would be just as clear to other Romans as someone saying March 11.

And furthermore, the system lasted 2,000 years, well into the Renaissance, he wrote. This meant Shakespeare could include the line, and expect his audience to know what he meant.

Test of time

However, just four hundred years later, the ides seems set only to survive as a literary and historical reference - in spite of it being the date by which debts (including Caesar's) were usually settled.

Professor Eileen Barker, of the London School of Economics, said it was a shame but the ides probably only had significance for schoolchildren reading Julius Caesar.

"I was thinking about this when I saw what date it was, and I thought no wonder I'm feeling awful," she said.

One significant historical event that fell on the ides of March is, perhaps, worth noting. It was on this day in 1876 that Test cricket was born.

Reason for anyone to beware? Perhaps for the English.

It was against Australia.