It is true that JEP have accepted Test 1 for the current valuation, despite their pretty scathing criticisms of it. However what drives 'de-risking' is not Test 1 as such but the way USS chooses to interpret it. 1/
"Test 1: a test designed to measure whether or not the long-term risk in the DB section of the scheme is within the risk appetite agreed between the trustee and sponsoring employers. 2/