United Kingdom
Pembroke Yeomanry Cavalry (Castlemartin)

Of all the Yeomanry regiments, the Pembroke is the one which fulfilled its original purpose, as it was involved in the repulsing of an oddly attempted "invasion" of England in 1797 - an altogether very strange affair in all respects. The related battle honour, "Fishguard" was awarded quite later (in 1853), and is the only battle honour conferred for fighting on British soil.
The uniform is dark blue with white facings and lace.

Cartes-de-Visite Cabinet Card

For a very entertaining read on how the French invasion was defeated :

The battle of Fishguard