"Instructors are required to complete either form SRG 1119E or SRG1157..."
But those forms are for EASA licences, not National licenses. The hour with an instructor relates only to the NPPL, there are pilots with UK National licences with SLMG ratings issued prior to 2008 and they can be revalidated on the basis of 5 hours in 13 months. See
ORS4 No 1192