They aten't dead! At least one of them had hatched a short while ago. I followed all the instructions on this page http://www.aquaticcommunity.com/killi/triggers.php and waited four hours before going back to inspect the little dish of water the peat has been mixed into. Was telling myself that I'd give it until tomorrow, when something moved in the peat. Too tiny to see properly, but a definite wriggle that wasn't there earlier.
Everything I've read says they are very susceptible to fungus so the odds are against the survival of any that do manage to hatch. I've given them a little wad of water moss to hide in, a fraction of a drop of fry food, and set the brine shrimp hatchery up in the aquarium for the very first time. The newly hatched fishes are supposed to be fed on baby brine shrimp, but since I wasn't really expecting the fish eggs to hatch I didn't bother setting up the brine shrimp hatchery beforehand. It is now bubbling away in a corner of the aquarium, making a delightful mad scientists laboratory background noise.
Since there's a high probability that any baby fish that do hatch won't survive to adulthood I have taken out my celebrations in advance and feasted on the first asparagus spears of the year with a couple of boiled eggs (chicken not fish).