A fascinating case where the taxpayer's wife deployed clever technical arguments & won! Good for her. Amazing stuff and well done to the sensible judge too (unlike most other FTT judges who are biased in favour of HMRC).
Presumably the same argument can be used for the other step 7 income tax charges here:
e.g. see para 49 here: https://www.bailii.org/ew/cases/EWCA/Civ/2019/1719.html
This DA point seems to be supported in this case despite para 42 comments: https://www.bailii.org/uk/cases/UKUT/TCC/2020/120.pdf
[Edit 2.7.20] I should have added also that para 28 of UT Robertson (when read with paras 9 and 17(6)) appears to have left the issue open: https://assets.publishing.service.gov.uk/media/5d1b57b3e5274a08d85bee2e/...