I'll be honest - it has been a long time since that day! I cannot remember what was said about the fuel type. The sheets state JET A1, but having never fuelled that particular plane, I have absolutely no idea. I am (especially now) assuming that it must have been AVGAS in the tanks - and not JET A1!
Thanks to my new acquired knowledge, and a little Google... It seems improbable that a PA28 was in fact fitted with a turbine / jet-prop engine. (a good pilot never stops learning right?)