Gather a letter and a number from this cache to find the Bonus cache.
To find this cache: Note- It's best done while travelling Eastwards. (From West to East) First, visit a postbox at the above co-ords and get its postcode. It's printed on the info on the front of the box, towards the bottom. The 'code is: HPmn mop
You'll find the cache at: N51° 4o.(m multiplied by o)(m+(p-n))o W000° 5m.op((p-n)-m)
You'll need to leave the track, just. Good luck!
Caches along the Phoenix Trail:
Thame Moreton Circle - 01*, GC01-West Ender, INDUSTRIAL REVOLUTION 1 (short detour)*, GC02-Not the Ivy!, GC03-Rocky Moment?, GC04-Sleeper Cell, twixt Thame & Towersey*, GC5-Beware the Rabbit, GC06-Classic Hide, Old SideTracked - Towersley Halt*, GC7-Rest Awhile, GC08-Off Track, GC09-Yumcrete , GC10-QEF?, GC11-Tree Cover, GC12-Stand Sit Jump!, GC13-Reflective Space, GC14-Lost Signal, GC15-Blasted Thing!, GC16-Eclipse, GC17-First Class, GC18-Rooky Error, GC19-Isolated Location, GC20-Bridge Hand, Virtual Insanity*, GC21-Gated Community, GC22-Antlers, GC23-Front Door, GC24-Around the Bend, GC25-East Ender, GCB-Bonus!
*Not part of the Geolympix Cyclerama series, but you may pass close-by along the way.