According to Sky News, Russell Reynolds Associates has been called upon to conduct the search for a replacement.
City sources told the publication that Samuel is likely to step down from his role in the £47bn wealth management and professional services group within the next 18 months.
Currently the chair of John Laing, an infrastructure investor, Samuel has previously chaired TSB, Ecclesiastical Insurance Group, and Howdens Joinery Group.
He assumed chairmanship of Tilney Bestinvest in 2017, prior to its £1.8bn merger with Smith and Williamson.
Following the completion of the deal, which was facilitated by a cash injection from the private equity firm, Warburg Pincus, the combined group now acts as the UK’s sixth-largest professional services company by fee income.
Tilney Smith and Williamson is currently run by Chris Woodhouse, chief executive, who has formerly acted as executive at RAC and Debenhams.
Accountancy Today has contacted Tilney Smith and Williamson for comment.