HMRC have updated the Business Income Manual following the Court of Appeal decision in Eclipse Film Partners No 35 LLP v HMRC  EWCA Civ 95.
BIM 20103 now includes the following:
“[The Court of Appeal decision] demonstrates that it is important to consider whether there is any risk to the activity carried on by a person when determining whether that person is carrying on a trade. Fixed returns from an activity which are not related to the success of that activity may indicate the absence of a trade. However, much like any other factor that needs to be considered when determining whether a person is trading, the existence of risk is only indicative and is not determinative.”