After taking some further advice we have finally done it.
I put Perry into a clean tub (with a lid) along with 8 smaller crickets and he ate 5 of them....Whoo hoo.
Im so happy
Once he has had a couple of feeds on the smaller crickets I will see what else he likes. Didnt seem to keen on meal worms the other day but they were quite big too so maybe I had best get some smaller ones again.
Such a relief.