From: Stringsinger

It seems that the Cittern could be a national English instrument. Also,
for obvious reasons, the Elizabethan lute.

With all due respect - how the bloody hell can it be a national instrument when there's only one man and his dog playing it? If you were asking "What was Elizabethan England's National Instrument" then maybe.

If it's a national instrument presumably the nation should know what the hell you're talking about?