I'd say a very fitted UK 14 more roomy UK 12 (or US 8-10). 20.5 pit to pit. 22.5 shoulder to cuff.
Stunning coat - very good vintage condition. The item "Ladies vintage COUNTY red leather double breasted COAT UK 14 12 long line duster" is in sale since Saturday, July 27, 2019. This item is in the category "Clothes, Shoes & Accessories\Women's Clothing\Coats, Jackets & Waistcoats". The seller is "sheba-knows-best" and is located in Wirksworth, Derbyshire. This item can be shipped to United Kingdom, Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Australia, United States, Bahrain, Canada, Japan, New Zealand, Hong Kong, Norway, Indonesia, Malaysia, Singapore, South Korea, Switzerland, Taiwan, Thailand, Bangladesh, Belize, Bermuda, Bolivia, Barbados, Brunei darussalam, Cayman islands, Dominica, Egypt, Guernsey, Gibraltar, Guadeloupe, Grenada, French guiana, Iceland, Jersey, Jordan, Cambodia, Saint kitts and nevis, Saint lucia, Liechtenstein, Sri lanka, Macao, Monaco, Maldives, Montserrat, Martinique, Nicaragua, Oman, Pakistan, Paraguay, Reunion, Turks and caicos islands, Aruba, Saudi arabia, South africa, United arab emirates, Ukraine, Chile, Bahamas, Colombia, Costa rica, Dominican republic, Guatemala, Honduras, Jamaica, Kuwait, Panama, Philippines, Qatar, El salvador, Trinidad and tobago, Uruguay.