Ok, so a random welsh MP suggests that the welsh dragon should be represented in the union jack. The Daily Telegraph runs a contest for a new one. The winner is, with 55% of the vote, is this.
That's the union flag, with the symbol of the Great Gurren Brigade on top. The designer even qoutes the series. I've been making references to Gurren Laggan for sometime. If you haven't investigated the series by now, you should. If only as a conversion starter.