As a senior bureaucrat in the Home Office, political assignments like receiving foreign emissaries would typically not be assigned to Arthur.
The main reasons involve two factors: firstly, the Foreign Office is unwilling for its responsibilities to be meddled with by other departments. More importantly, Viscount Palmerston, the Foreign Secretary, does not trust this reckless man who caused a lot of troubles in the Caucasus.
However, Sir Arthur Hastings is not only the Executive Deputy Secretary of the Home Office but also the Queen's appointed non-resident Royal Steward.
And receiving foreign emissaries who are visiting London for the coronation ceremony, although nominally belonging to diplomatic activities, in essence, if viewed from the old perspective, is more of a royal protocol event within the jurisdiction of the Palace Minister's Office.
After all, foreign affairs between nations, in essence, are actually derived and refined from royal activities.
