I recently bought the much acclaimed Sub-Roman Brits from Splintered Light Miniatures. Unfortunately there just wasn't enough time to paint the 32 spears so I had them done in Sri Lanka, except I told them I wanted to do the shields. (THey did a good job as usual.) I wanted them to look decidedly late Roman and used the Notitia Dignitatum as a basis for many of the shields. I don't care that some were used in Africa, Italy and Gaul, I just wanted ones I liked and wanted to portray the army as trying to keep the Roman traditions alive. I added some Christian symbols and purposely tried to make some look like the soldiers themselves had added it over existing Roman patterns.
I did paint all the cavalry myself, including King Arthur's Madonna and Child shield. The figs are awesome as you can see. Sorry, the photos are from my camera and not the best.
Here's King Arthur and his famous heavy cavalry.