Instructions:The terms and conditions on the coupon states:
1. Purchase one Authentic Thin Crust pizza at full price and get another free at any Papa John's site or by visiting www.papajohns.co.uk and entering promo code ARPJ01
2. Not valid without the daily mirror coupon.
3. Valid until 5 Febrary 2009
4. Free pizza must be of equal or lesser value than the first
5. when ordering via the Papa John's website the customer must reside within a Papa John's delivery area in order to be directly routed to their local store
6. Some areas have restricted delivery
7. not valid with any other offers
8. offer is subject to availability
9. delivery offer applies to minimum order value of £8.99
10. offer excldues papa john's stores located in Butlins and Haven holiday parks.
I was reading the newspaper and spotted this in the Mirror, I'm not sure if you can get away with number 2 in the terms and conditions.
I havent tried it myself, so if it works any feedback would be great.
Edit: Seems that the code works for "original" based pizza's too :)