In Jane Austen's day there were three types of marriage licenses available in England; the reading of the banns, a common license, and a special license.
The reading of the banns had the advantage of being free and consisted of the minister reading out the names of people who wished to marry during church services on three consecutive Sundays. If no one objected, the bride and groom would then be permitted to marry in their parish church within the next 90 days between the hours of 8 am and 12 noon. If the bride and groom belong to different parishes, it was required that the banns be read in both and the couple could then marry in either parish church.
A common license cost 10 shillings and was generally the preferred method for people who could afford it. The vast majority of Jane Austen's characters would have been married by common license. A common license could be issued if either the bride or groom had lived in the parish for at least four weeks and permitted them to marry in that parish church between the hours of 8 am and 12 noon.
A special license was the most expensive type of license, costing between 4 and 5 pounds, and were issued at the discretion of the Archbishop of Canterbury. A special license permitted a betrothed couple to marry at a time and place of their convenience, though they were encouraged to marry in churches. The only people who could obtain special licenses were peers and peeresses, their children, baronets, knights, members of Parliament, Privy Councillors and Westminster Court Judges. Fitzwilliam Darcy would not be eligible for one, though his cousin Colonel Fitzwilliam would be.
Jane Austen, David M. Shapard, ed., The Annotated Pride and Prejudice.
Jane Austen, Pat Rogers, ed., The Cambridge Edition of Pride and Prejudice.
Joan Klingel Ray, Jane Austen for Dummies.