Until May 1539, he was Henry VIII's ambassador in Brussels. In late 1539, Anne of Cleves was due to come from the German principality to England, and Wriothesley was to lead the naval escort. On 27 December the Princess arrived at Deal in Kent, from whence she was shown to Dover Castle; on New Years Day the party reached Rochester Castle. Wriothesley continued to support Norfolk's Catholic party, but only when it suited him at court, as parties emerged between the reformists and conservatives. In the absence of a predominant figure the Council became more conciliar towards the end of the reign. Having been sent on diplomatic errands abroad, in 1540 Sir Thomas Wriothesley was made one of the king's principal secretaries (a position he held jointly with Sir Ralph Sadler), acting as Secretary to the Privy Council. Dividing the duties, Sadler's was personal secretary to the King, whereas Wriothesley's responsibilities were purely political. Wriothesley was rewarded with the dissolved abbey of Titchfield for good service to the king. He rapidly converted it into a country house which became the family's ancestral seat. Wriothesley's noble parentage and strong personality enabled him to dominate the commoner Sadler. Knighted in 1540, Wriothesley made friends with Sir Anthony Browne of the refounded Gentleman Pensioners, who acted as an armed bodyguard of the King pursuant to the Greenwich Ordinances. The expansion of the Pensioners from 50 to 350 members was an expansion that signalled the resurgence of the conservative noble faction at court during the 1540s. Wriothesley, having earned his place at court as a faithful attendant to Thomas Cromwell, instead turned traitor in 1540, telling the king that Cromwell was indiscreet over Henry's inability to consummate his marriage to Anne of Cleves. This news, coupled with the Cleves alliance threatening war with Emperor Charles V, proved Cromwell's undoing. Wriothesley happily lied to the Council, and betrayed his master, in order to take his place beside the king.