While studying in Dublin, Blackham worked as a Midwife for the Rotunda Hospital where he travelled the city by bicycle, delivering babies.

In order to gain promotion to the rank of Major he took an exam in the newly formed Army Medical College in London.

Blackham's arrival in India in 1908 for his second tour coincided with an effort to revive interest in ambulance training.

He was an experienced lecturer and examiner of the St John Ambulance Association and as an officer he was asked by Lord Kitchener to accept the position of honorary secretary.

Blackham received the Distinguished Service Order for ministering to the Viceroy of India, Charles Hardinge, after an assassination attempt by Indian nationalists in 1912.

At King George V 1913 Birthday Honours Blackham was awarded - Companion of the Most Eminent Order of the Indian Empire for commanding the station hospital at Jutogh, Simla.

[7] Despite Blackham's very active military life during World War One, he found time to obtain further medical qualifications, he became F.R.F.P.S.Glas.

[2] During the Irish Civil War (1922-1923) Blackham was posted in Dublin as Assistant Director of Medical Services.

In 1903, Blackham joined the Middle Temple in London and passed the bar final examination without attending a single lecture.

At the outbreak of the Second World War, Blackham came out of retirement to serve on the Medical Personnel Priority Committee and he oversaw the care of soldiers in civilian hospitals.

Blackham was highly decorated for his military services, receiving many awards, including the Croix de Guerre (twice awarded), Chevalier of the Legion of Honour, Distinguished Service Order, Kaisar-i-Hind Medal, Companion of the Order of the Indian Empire and special member of the Japanese Red Cross Society.

In 1932 he financed the publication of a collection of poetry by his cousin Henry Hamilton Blackham (1817–1900) titled The Bard of Clanrye which was published by Robert's nephew Aodh de Blácam.

At the outbreak of the Second World War in 1939 he wrote a first-aid guide for civilians called "Air Raid First Aid".

In his obituary in the British Medical Journal, Dr. P. T. Parsons-Smith wrote[9]- ..In addition to his attractive personality, Blackham was a man whose long and distinguished career was characterised by his Kindly nature, his enthusiastic approach, and his unfailing sincerity.

His most noteworthy quality was his high sense of duty, and, whether it was in the Army, his civil appointments, in Freemasonry, or other of his various important offices which he filled, his capacity for leadership and his administrative skill proved to be of outstanding value.

In conversation he was dignified, impressive, and unhampered by convention; he was skilled in the art of discrimination, he expressed his opinions with a sincerity which made it difficult for his opponents to take offence, his advice was founded on sound convictions, and he achieved a high reputation as a fluent and convincing speaker..