Field Marshal tunic 1872

Hi,
Recently I got an article published by Journal of Society for Army Historical Research, named: "The evolution of the tunic of staff of British army 1855-1939". It was written by N P Dawnay. In the article, author mentioned that from 1872 to 1880, Field Marshal wore shoulder cord like General officers after 1880. On the shoulder cord, crimson and gold crossed batons were present. He put Dress regulations for the officers of the army 1872 and 1874 as references. When I investigated this in DR 1874, I have found no such information.
Can anyone confirmed me about the tunic design for British Field Marshals during 1872-1874 please?
Cheers
Shams

Shams,
I don’t know if you have had an answer, but here’s my penny worth.
As far as I’m aware regarding rank badges and tunic.
Many of the Victorian paintings of field marshals are not actually wearing the uniform of a field marshal, but that of general or even colonel.

In 1855:
Field Marshal, crossed batons within laurel leaf.
General, 1’’ gold oak-leaf lace top and bottom of collar with silver crown and star.
Lt. General, 1’’ gold oak-leaf lace top and bottom of collar with silver crown,
Maj. General, 1’’ gold oak-leaf lace top and bottom of collar with silver star.
Brigadier General, ½’’ staff pattern lace with crown and star.

The rank badges were removed from the collar onto the shoulder in 1880 with:
Field Marshal, crown over crossed batons within wreath.
General, silver crossed sword and baton with crown and star above.
Lt. General, crossed sword and baton with crown above.
Maj. General, star.
Brigadier, crossed sword and baton.
Field Marshal and Generals tunics and shoulder boards were the same design with the appropriate lace and insignia.