Theoden's shirt, undertunic, boots and black pants are very similar to those of the court costume. The pants and boots are exactly the same. The shirts worn by both Theoden and Gamling are mulberry tussah silk which was customed dyed to match photos of the film characters and then aged. This photo shows the texture of the silk.

This is one of the shirts prior to dying. Note the red leather tie at the neck. Since I was not sure how leather would take fabric dye, I started with a shade close to the one I wanted to have at the finish.

And here is one of the finished shirts. This one belongs to Gamling.

Theoden's undertunic is cotton twill with leather lacing. Metal grommets were used as the film seems to show them in the original costume. It was again custom dyed since I was unable to locate a similar green. The hand embroidery is on the collar only, as on the film costume and is the same as the design I developed for the court costume. The arm openings on this under tunic are a bit larger to allow for complete freedom of movement, but it looks very much like the one on the court costume page.

Gamling has an under tunic of brown ultrasuede which is based on the single photo I have of the character out of his armor, during the toasting scene after the battle of Helm's Deep.

Both Theoden and Gamling also have sashes of mulberry tussah silk that they wear with their armor. Gamling wears his on top of his mail coat, under his belt, as do all the Royal Guard of Rohan. The King wears his on top of his mail skirt, under his cuirass. Presumably to protect the skirt from wearing against the metal of the breastplate. This can be seen in photos of the costume taken from the back during costume tests.