In the new Upstairs Downstairs is Lord Hallan A.K.A Baron Vansittart?

In the new T.V program Upstairs Downstairs is Lord Hallan A.K.A Baron Vansittart? In new Upstairs Downstairs the main character is Lord Hallan,an Aristocratic,a Diplomat who became the chief,number one civil servant of Foreign Office.Of course,Hallan is fictional character but he has a lot simlairs to Robert Gilbert Vansittart,1 Baron Vansittart who was an Aristocratic and Diplomat who 1930 became the permanent secretary of foreign office.
This was written about Vansittart in John Colville's book THE FRINGES OF POWER 10 DOWNING STREET DIARIES 1939-1955." Sir Robert Vansittart, made a peer by Churchill in 1941,was a striking intellectual ability,profound literary knowledge and poor judgment.He was made Permantent  under secretary when I join the foreign Office in 1937  and had established a high reputation at home and abroad.Indeed it was too high for his comfort ,Anthony Eden much dislike the general belief that Van was power behind the his throne and the real originator of all diplomatic intiatives.With the support Chamberlain who ,loke mostP.Ms,resented the Foreign Office Van was replace.
When Churchill came to power,Van doubtless hoped for renewed influece since he constantly warned of the German danger  in years before the war,but Churchill also dislike the  foreign office so Van never regain his power.