Not to worry, I haven't done anything wrong (well not that I know anyway).. just that today I am going to Coventry to attend a conference on a recording system for lectures..
But it set me thinking as to the origins of the phrase, and a quick search of the internet revealed :
It is quite probable that events in Coventry in the English Civil War in the 1640s play a part in the phrase. Coventry is an industrial city in Warwickshire, England. In the 17th century, when this phrase is supposed to have originated, Coventry was a small town. It is suggested that the phrase originated from people being physically sent there as a punishment.
One story is that Cromwell sent a group of Royalist soldiers to be imprisoned in Coventry, around 1648. The locals, who were parliamentary supporters, shunned them and refused to consort with them.
The other story is that there was once a garrison in Coventry, a fact which was massively unpopular with the local inhabitants (usually because of the drunken conduct of the soldiers), so much so that they would not even speak with any of the soldiers stationed there and certainly the women were strongly discouraged from discoursing with them.
Hence, it was effectively guaranteed that any soldier posted to Coventry would be in for some serious shunning.
I like the second idea, but the reality is we will never know.