TZ is Israeli Military Industries, Natzeret, Ilit, Israel. Headstamps are sometimes marked in hebrew and sometimes as TZ or TZZ.
Israeli cases have been re-used for other purposes, eg theatrical dummies and blanks in New Zealand. I believe that is the situation here, with Israeli cases being used to load British made EOD blanks.
Ron Fuch’s .50 cal book lists a couple of HADL XL1E1 EOD blanks loaded in 10/87 and 11/87 both using TZ86 cases, the book also lists an L.E.L L1A1 EOD blank loaded in 5/92 that uses a TZZ88 case.
(Tim G , as Ron’s book lists HADL XLE1 1987, and LEL L1A1 1992, could it be that Leafield was previously Honeywell, not vice versa?)