Once he had returned to London, Thomas entered the household of a merchant named Osbert Huitdeniers (“Eight-pence”). Osbert and Thomas were related, perhaps through Thomas’s mother. Thomas kept Osbert’s accounts for over two years. If, as his name suggests, Osbert was a moneylender, the years Thomas spent in his service must have provided him with practical expertise of great value to employers in the developing economy of the twelfth century. Life in London in the early 1140s would also have provided an education in national politics because this period saw the height of the rivalry for the throne between King Stephen (r. 1135-54), nephew of King Henry I (d. 1135), and Henry’s daughter Matilda, “the Empress.” London was in the thick of events, and an intelligent, ambitious young man would have learned much by observing the ins and outs of the struggle for the throne.
In the middle 1140s, certainly by 1146, Thomas left Osbert’s household and entered that of Theobald, archbishop of Canterbury. The archbishop of Canterbury was the highest church official in the kingdom of England: the only other archbishop was at York, but York was in the north, was relatively poor, and had only one suffragan (that is, subordinate) bishop, whereas Canterbury was located close to the center of power, was extremely wealthy, and had nearly 20 suffragans in England and Wales. Moreover, while all bishops were among the great lords of the land, Canterbury, by virtue of his leadership of the church and his wealth, was the most prominent of them. Like all great lords, he expected to be consulted by the king on important matters, he regularly attended the royal court, and the king expected his loyal support of royal policies. In the conflicted politics of the 1140s, a successful archbishop needed to be a consummate politician. Theobald was.
An active archbishop required a large staff, some of them based in the cathedral church of Canterbury but many of them traveling with him as he moved about the country. Like all great landowners and lords at this time, the archbishop and much of his household were itinerant rather than residing primarily in one place. When he joined Theobald’s household, Thomas became a member of an elite group of highly able functionaries in one of the major centers of power, secular as well as religious, in England. It is no accident that, of the members of Theobald’s household, four later became archbishops and another six became bishops. Thomas initially was one of the second tier of the archbishop’s officials, but he rose rapidly. Theobald allowed him to study law at Bologna and Auxerre for a while. He accompanied Theobald to the Council of Reims in 1148 and represented the archbishop at the papal curia several times. In late 1154, Theobald made him archdeacon of Canterbury. All over Europe, the twelfth century saw the rapid advance of administrative techniques, and this was as true for the church as for secular governments—or even truer. As bishops developed the administration of their dioceses, the archdeacon emerged as the most important official engaged in the day-to-day management of affairs. To be archdeacon of Canterbury was, therefore, to be in some sense the second in command to the most important person in the kingdom after the king himself. Because Thomas had neither important family connections nor important patrons promoting his career, his rise must be credited to his administrative skills and, no doubt, his ability to ingratiate himself with his superiors.