Ozmacca and artbrooks, quite right, the white cockade denoted sympathisers to the Jacobite cause in Britain (I say Britain rather than Scotland, becuause during the rising of the '15, there were a number of Jacobite rebellions in North-west England, which fizzled, and during the '45, a Jacobite regiment was raised in Manchester.

In Scotland especially, cockades were necessary, as several clans (especially the Campbells, but also the Munros, Mackays and others in Caithness and Sutherland) declared for Hanover. It was always useful to know who was burning your house down ...

Read James Prebble's book, "Culloden" for more information.

In the British Army, some units are entitled to wear a "hackle", a small feathered plume rather like a fishing lure, behind the beret badge. If I remember, these are the Royal Regiment of Fusiliers (red over white), the Royal Welch Fusiliers (white), the Royal Greenjackets, the Light Infantry and the Royal Irish Regiment (green). I don't think that this was anything to do with a cockade, but I may be wrong.

Officer cadets are supposed to wear a white patch behind their beret badge. A good way of saying, "Aim here", I suppose. The issued patch is the size of a dinner plate. Most savvy O/Cdts use the cut-away bottom of a yoghurt pot instead.