[U.K] Revenue and Customs Brief 15 (2015): HMRC response to the Supreme Court decision in George Anson v HMRC (2015) UKSC 44 25 September 2015

…[T]he [Anson] decision is specific to the facts found in the case. This means that where US LLCs have been treated as companies within a group structure HMRC will continue to treat the US LLCs as companies, and where a US LLC has itself been treated as carrying on a trade or business, HMRC will continue to treat the US LLC as carrying on a trade or business.

[It is understood from a U.K. correspondent that the "treating" is by HMRC, who have long regarded US LLCs as "opaque" (see INTM180030 below) and are effectively saying they will continue to do so.]

…[T]he [Anson] decision is specific to the facts found in the case. This means that where US LLCs have been treated as companies within a group structure HMRC will continue to treat the US LLCs as companies, and where a US LLC has itself been treated as carrying on a trade or business, HMRC will continue to treat the US LLC as carrying on a trade or business.

HMRC also proposes to continue its existing approach to determining whether a US LLC should be regarded as issuing share capital. Individuals claiming double tax relief and relying on the Anson v HMRC decision will be considered on a case by case basis.