flight test?
 

Unusual looking aircraft over Skegness noon on Monday 21st March.
Thought it was going to be the usual Tornado but on closer inspection was delta type aircraft. Looked more like a flying shuttlecock? Flying at several thousand headed out to sea, couple of s turns then headed back to west.
Sounded as though it had a single engine and whistled rather than roared. Reminded me of some kinda fifties DH or Bristol type.

Anybody know what it was? was it a test flight.

How about a Typhoon? Even though it is late coming into service I don't think it is a museum piece like the other aircraft you mention! Could have been one from CGY - apparently they have heaps of thrust so they don't need to roar around at high power settings. Skegness is a recovery point for CGY aircraft, though most of the Typhoons are based at Warton I believe, one might have 'escaped' to visit its future home.

SG