Glengarry bonnet
From Tardis Wiki, the free Doctor Who reference
The Glengarry bonnet was a brimless cap from Scotland with a crease down the crown, often with ribbons dangling at the back.
Alistair Gordon Lethbridge-Stewart wore a Glengarry bonnet as a colonel of the Scots Guards 2nd Battalion when he first met the Second Doctor, Jamie McCrimmon, Victoria Waterfield, the Great Intelligence, and Robotic Yeti during the London Underground Incident. (TV: The Web of Fear)