This signal flag represents U (uniform).

Nearly all maritime nations recognise the same flag signal alphabet. They were used to spell out short messages to each other between ships.

Strung end to end and hung bow to stern from the rigging they were used to dress up ships for ceremonial and festive occasions.

Today they make great coastal home decor and are meant to stand up to the ocean winds. This flag is made from a cotton/nylon blend.

It has some wear and tear from it's life at sea as you can see in the photos. 

Measures approx:95cm x 115cm