It is well-known that some regiments in the British army were cutting down regimental coats during the American Revolution. The practice was far from universal but, on the other hand, it was not a rarity. Below are good examples (L to R): a period drawing of a cut-down Royal Artillery coat from the 1777 campaign of General Burgoyne, a modern drawing of this same coat and finally, an actual coat still in existence:

     On the left is a period drawing of a British Royal Artillery coat. The artist was Friedrich von Germann, a German soldier who served in Burgoyne's army. It is in the New York Public Library's Print Collection. In the centre is a picture based on Germann's drawing (from Uniforms of the American Revolution). On the right is an actual coat which still survives: the uniform of Lt. Jeremiah French, 2nd Battalion, King's Royal Regiment of New York (from the book The Loyal Americans, Canadian War Museum).

MORE ON CUT-DOWN COATS

62nd Regiment of Foot, 25 May 1775, Inspections return:
". . . Uniforms very short and hats very small. Clothing - coats cut so short that I must call them jackets."
------- British Military Uniforms 1768-1796, The dress of the British Army from official sources by Hew Strachan (UK, 1975), page 245.

". . . All companies of the Royal Yorkers wore coatees, or jackets, as opposed to full length regimental coats, as the latter had proven to be less servicable, their tails continually catching on brush in the woods . . . The practice of wearing coatees, sleeved waistcoats, and slouched or flopped hats even by mid-war was well established."
------- The Burning of the Valleys by Gavin K. Watt, page 310 (endnote)