Christians and Cathedrals

Indeed, it is hared to see the cathedrals serving Christians as a whole. They were built essentially for the clergy and upper classes, and to some extent for well-to-do townsmen.  The choir-arm was a chapel reserved exclusively for the canons in a secular cathedral, or the convent in a monastic one. The laity had not part in the services, and indeed when they stood in the nave (which had not benches or chairs), the high altar would be obscured by the screen or pulpitum. Sometimes no eve was built at all, as at Beauvais. Usually, it formed a vast vestibule for the choir, used for professional purposes. It was not intended for lay worship except where, as in a few cathedrals, buildings it had involved knocking down a parish church. Then an altar would be set up and function. But most naves were big, empty and dirty places, not elaborately decorated like the "clerical" part of the building. Often they were used for trade. In 1554, under "Bloody" Mary, the City of London corporation forbade anyone house the nave of St. Paul's as a short cut to carry casks of beer, or loads of fruit and fish, from the river to the markets.

Paul Johnson, A History of Christianity, pg. 227