Busted, Rob! Yes, it was a Gloucester high school (with maroon blazers) Cards were apparently sent to Cheltenham (we were never able to meet the machine itself). The card punches I used were big chunks of metal with typewriter like keys on top that you had to use pairwise, pushing the pins directly through the cards (satisfying ker-chunk) and sweep up the chads afterwards. They tried to switch to mark-sense cards but those were horribly unreliable, even with 4B pencils. Yes, the PET’s tape drive was near-useless.