Possible Clues:

• Member of any of the West Germanic tribes that settled in Britain from 5th century AD
• Norman Conquest victim
• Language in a slogan that's silly - Number 10's spinning
• County, one unknown, in unidentified language
• Old English
• Old English instrument to feature in a long jazzy number coming up
• Old English language before 1100 or 1150AD
• Native or inhabitant of England prior to the Norman conquest
• Battle of Hastings loser
• Fifth-century invader