Ledbrooke was a Military Surgeon in the Bucks Militia. Documents at the Huntington suggest he was an eye specialist. It is possible he was initially recruited by the Buckingham's to care for Mary Nugent; he later offered more general medical advice and treatment to the family. Ledbrooke was still on active service in late 1810 and had joined the family by March 1812 . 

On 29 October 1819, the Prince Regent issued a proclamation that all Out-Pensioners of Chelsea Hospital were to be examined for fitness for Garrison Duty. Ledbrooke was ordered by the Army Medical Department to conduct an medical examination and particularly to comment on the efficacy of new treatment by Sir William Adams (see the order).

While continuing his medical duties for the family, Ledbrooke had by January 1820 become a general factotum for the first Duke and Duchess. He oversaw accounts and, to some extent, managed the estate stewards. 

Tobias died before January 1843 (HEH STG Box 382 (58)).

His name is also spelt Ledbrook, especially the First Duke (but not Ledbroke as used in Beckett). Ledbrooke is the spelling he uses himself.