The old castle was long used as the County prison. About 1653, a strong building of brick and stone was built within its precincts to serve as a House of Correction. The entrance was by way of the lane just south of Edgar Tower, and the new buildings of the King School occupies the site.
In 1783, it suffered a virulent attack of gaol fever, and in 1788 it was visited and condemned by John Howard, the prison reformer. The County magistrates spent £3,431 on its improvement but the building was old and extremely insecure. In 1793, there had been numerous escapes, and thereafter escapes were frequent. Proposals to build a new gaol were put forward in 1802, but the landowners in the County and City protested at the cost and held a meeting at the Guildhall in April 1802. So strong was their influence that the plans were shelved and nothing was done. But in 1807, Chief Baron MacDonald arrived at Worcester for the Assize and found that the prisoners in the important cases had vanished! His Lordship warned the Grand Jury that the County would be heavily fined if matters were not put right. This threat hastened the matter, and the new prison was built in Salt Lane in 1813.
The prison had been one of the sights of the City, and on Assize Sunday (the Sunday during or immediately following the Assize) prisoners were shown to the crowds, the visitors giving 6d. to the gaoler for pointing out those condemed to be executed. There was an open ironwork railing between the debtors and the felons and they could communicate as they pleased. Visitors to the debtor's were not searched - only visitors to the felons. The debtor's common room was far to small, and was also used as a chapel. There was no special room for the condemned criminal; he was chained to a post by day near the door of the common-chapel room. There was a regular transference of prisoners to the 'transport's which went down river to Bristol, whence they were shipped out to the plantations.
Executions took place on Red Hill and the procession to the gallows was often a rowdy affair, though sometimes there was sorrow at the loss of a young life. Berrow's Journal reported the execution at Worcester, of a young soldier aged 23, for desertion: 'the condemned man walking with his shroud behind his coffin, from the Gaol to the place of execution, reading from a book - the procession was the most decent and solemn ever seen on such an occasion'.
So many felonies carried the death penalty that there was often a reluctance to carry out the sentence, though a 'hanging judge' might leave a dozen or so in prison awaiting the final word from London. Sometimes the authorities there moved in a strange and cruel way, as the following report shows: 'In the old prison of Worcester was a boy of some 13 or 14 years, who had for some offence been sentanced to be hanged, but the judge, because of his age, respited the death sentence, and the London authorities seem to have gone on extending the respite. In this way, two years went by. The boy in the meantime, was allowed a good deal of liberty, so much so that he could have escaped had he so desired. An old inhabitant of Worcester related that one day the boy was playing at ball in the yard with some debtors, full of life and glee, when suddenly to the utter astonishment of the jailor and all his associates, there came an order from London for his execution. Why he remained so long forgotten, and why so extreme severity fell on him no one can tell, but his case was considered a very hard one, and was commby the whole City. Bill's informant saw the poor boy conducted to the execution.