1. National Dress in Britain

2. Scottish National Dress
Today traditional dress for men in Scotland is a kilt with shirt, waistcoat and tweed jacket, stockings with garter flashes, brogue shoes and a sporran. A bonnet is often worn displaying the clan crest.
Traditionally ladies don't wear kilts, they do however wear dresses or pleated skirts in a tartan material. More often though they wear a light plaid or shawl of tartan material,

3. Welsh National Dress
Welsh National dress is relatively young and not as famous as Scottish National dress. In fact there isn't really a National costume for men although recently through the rise of nationalism in Wales a tartan has been created and tartan trousers or kilts are often worn.
For the ladies the typical Welsh costume consists of a hat, made of black felt, with a high crown and wide brim. A red flannel shawl is worn over a crisp white blouse, and a full skirt made of wool with a black and white check pattern. Proper Welsh ladies always wore black woolen stockings and black shoes and carried a basket, made from willow withies.

4. Irish National Dress
With the revival of Irish dancing, the traditional Irish costume has become associated with the bright costumes worn by traditional Irish dancers. However in ancient Ireland people were more likely to be seen wearing 'leine' (Irish for shirt), trews (Irish for trousers) and long cloaks fastened with a brooch.
All in all there are a lot of myths and legends surrounding many of the so called 'traditional' costumes. Often when you do some real historical research you will find that they aren't that old or traditional.

5. English National Dress
Unfortunately the English don't really have a traditional National Dress as such. There have been calls over the years to create a costume, but as usual no-one can decide on what it should look like.