Chug, my original 1767 (1960) required simply day/night single engine or multi. The later ones, 1968,1971 and 1986 indeed specified each mark viz Shackleton Mk 3 and Shackleton T4.
No, my point was that the 1369 specified just Shackleton for instance, and surely the Air Sec, as was, should have been more interested on the employment options as stated by hours per type rather than the more professional 5200 series with individual mark breakdown.